I know this MPG topic has been beaten to death, and I apologize for bringing it up again, however I would like to propose a new approach to understanding this MPG issue. I am not an RX-8 owner (yet), but have been following this forum for quite a while. Like many others, I too am interested in trying to understand the cause of great variation in mpg among RX-8 owners as well as relatively low mpg in many cases. (I have a daily commute of 85 miles).

It is very possible that there may be a combination of several factors causing this MPG situation. There is a type of quantitative analysis called Multivariate Regression which takes multiple factors into consideration and calculates their relative importance in determining an outcome, in this case, mpg. I’d be happy to conduct the analysis as a fellow RX-8 supporter. I just need as many RX-8 owners as possible to answer the survey below.

Based on my prior forum reading, I’ve come up with a several potential factors impacting the mpg. We’ll have to keep the responses very simple and straightforward. (Answers as explanations won’t work). Please participate……..

1. RECENT Combined City/Highway Average MPG = ___________
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = ______

3. Driving Style =
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = ___________
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = ___________

6. Automatic / 6 speed = _____________

7. Octane (Number) of Fuel Used = ____________

8. DSC/TCS = Yes / No(Don’t Have or Fully Disabled)

9. Miles to Date = ___________

10. Approximate % Time Driving with Windows Open = ___________

11. Approximate % Time Driving with AC on = ___________

12. State = ______________
(I’ll later convert to Geographic Region)

Hope like hell I didn’t miss anything. I know this will be a pain – that many people have already responded to many threads regarding mpg. However it is very difficult to test one theory (eg. VIN # or Octane), when so many other contributing factors may also come into play. The analysis I am proposing takes all these factors into consideration simultaneously and identifies those which are important in determining mpg. If you are interested please respond. If you are not interested, well, please also respond………the more observations the better. I’ll post the results soon after receiving enough observations. For those that want to flame, hey, it’s my first post – have fun.

IMPORTANT: When responding, please complete all entries. If one thing is missing, such as Octane, then your entire response cannot be used. Thanks in advance for participating.

mod edit: results thread http://www.rx8club.com/showthread.php?t=13404&page=1&pp=15

1. 16.2mpg
2. 40%
3. B
4. 106206
5. GT
6. 6 speed
7. 92
8. fully disabled
9. 834
10. 30%
11. 2%
12. NM

1. 16.8 MPG
2. 40%
3. C
4. 101102
5. GT
6. 6 speed
7. 93
8. Yes
9. 8400
10. 0%
11. 25%
12. NH

Observation: This only reflects my milage for my last fill-up. When I'm traveling my mileage increases significantly due to all of the time spent on the highway (20-24 MPG). Likewise I have seen horrible fuel economy on track days (7.5 MPG) or when I have been fooling around (13 MPG). Will this variation skew your results?

I'd emphasize to respondents that all their answers be specifically related to the 'recent MPG' answer to question 1.
-jd.

1. RECENT Combined City/Highway Average MPG = 22
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = 85%

3. Driving Style = B
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = 101212

5. Model (eg. Base, GT, etc) = GT

6. Automatic / 6 speed = 6 Sp

7. Octane (Number) of Fuel Used = 91

8. DSC/TCS = Yes

9. Miles to Date = 4800

10. Approximate % Time Driving with Windows Open = 10%

11. Approximate % Time Driving with AC on = 5%

12. State = AL
(I’ll later convert to Geographic Region)

1. 14.80
2. 15%
3. A
4. 108837
5. GT
6. 6 speed
7. 91
8. Yes
9. 2914
10. 1%
11. 5%
12. CA

Speed Racer: Regarding your concern about skewing the results. As long as your responses to the questions regarding % Highway and Driving Style (?'s 2 and 3) are based on RECENT driving (in accordance with your RECENT avg. mpg), I believe the results should be o.k.

JDL is correct:

PLEASE NOTE: As JDL stated; All responses should be specifically related to the 'recent MPG' answer to question 1.

ie. % highway driving, etc. should be based on RECENT driving.

Here's another take on the issue. What if the speedo's are.."optomistic"? say 1.5 mph off. That would reduce the MPG. I think before you can establish a baseline. You need to use another method of calculation. If the speedo's are at fault, then all the data collection in the world will not show a thing.


my .02 yen

1. 22.9
2. 80%
3. Average
4. 105899
5. Sport
6. 6 speed
7. 93
8. Yes
9. 5000
10. 10%
11. 20%
12. Virginia

"What if the speedo's are.."optomistic"? say 1.5 mph off. That would reduce the MPG. I think before you can establish a baseline. You need to use another method of calculation. If the speedo's are at fault, then all the data collection in the world will not show a thing."

Good point Matt. I have a couple comments in response.

1. If the speedos are optimistic 1.5 mph, I believe that would actually yield a higher mpg, thus reducing the problem people seem to be having. For example, if the speedo read 50 mph too high, then the odometer reading would show much higher mileage, thus yielding a terrific MPG.

2. One of the goals of my proposed analysis was to better understand the great variation in MPG among RX-8 owners. If everyones speedo reads 1.5 mph too high, then everyone is impacted the same. Though the MPG results for everyone would be a tad bit higher than reality, it would not cause variation in MPG among owners.

3. I'm assuming the optimistic 1.5 mph reading occurs at roughly 60 mph. That equates to a 2.5% error, or similarly, for someone getting 20 mpg equates to 1/2 mpg. This is not near enough to muddy the results of the analysis.

1. 21.35 MPG
2. 85%
3. B
4. 101129
5. touring
6. 6 speed
7. 92
8. No
9. 7800
10. 5%
11. 2%
12. MD

another part of driving style that may be important is average speed / or normal cruising speed. mine is probably average 72, usually in the 75 +/- 5 range. Sometimes 68, less some times in the 90s. I'm not sure how my throttle use is as an 'average'. in town driving it's very easy going,1200RPM starts. usually. Then there's a hopefully daily 9K redline short burst. My fuel buying was 87 for several tanks; the last 4 have been premium. The MPG figure I gave is the last tank which was on the 3rd full premium tank since switching back from 87. Our local temps have been in the 45-60 range mostly recently. Running close to 32PSI; 5w/20 oil, usually no passenger or extra luggage -all possible factors as well.

1. RECENT Combined City/Highway Average MPG = 18.3

2. % Highway Driving = 10%

3. Driving Style = B

4. VIN Number (last 6 digits) = 106908

5. Model (eg. Base, GT, etc) = GT

6. 6 speed

7. Octane (Number) of Fuel Used = 91

8. DSC/TCS = Disabled (DSC off, but no squiggly lines)

9. Miles to Date = 1500

10. Approx % Time Driving with Windows Open = 0%

11. Approximate % Time Driving with AC on = 98%

12. State = Florida


How about adding spoiler/no spoiler and front lip/no lip?

But there are more variables to consider: Ambient temps, humidity, length of traffic lights (here in Tampa bay, some red lights are 3 minutes long), amount of time idling, Hills/no hills,
average MPH...just to name a few

1. 15mpg
2. 5%
3. B
4. 107764
5. GT
6. 6 speed
7. 91
8. fully disabled
9. 1500
10. 50%
11. 50%
12. California

1. 17.5mpg
2. 20%
3. B
4. 104226
5. GT
6. 6 speed
7. 89
8. yes
9. 1950
10. 20% (sunroof open 75%)
11. 5%
12. OH

norton, will your statistical analysis support multiple data sets per VIN?

I can imagine over time folks will have additional data for recent MPG calcs, perhaps with dramatically different driving styles, all-freeway, no-freeway, etc... I have several such data sets already.

Another data point you might want to include, then, is the rough #miles on the vehicle at the time of the data set. Perhaps just to differentiate the sets per VIN, or track another correlation to "new car break-in".

My motivation: well, for my break-in I took a 1200 mile road trip, yielding 22.58 mpg, which stands as my car's all-time best. I know the car's capable of doing 22+ mpg, but my last many tanks have settled more in the 14 mpg range. Clearly there a large range of data for each car.

Cheers,
-jd.

1. 17.5
2. 60%
3. A
4. 1011311
5. GT
6. 6
7. 93
8. Yes
9. 790
10. 2%
11. 5%
12. VA

I don't yet have enough observations to conduct the analysis, however I did notice one interesting thing while taking a quick look at the few observations so far. Looking at MPG and % Hwy, there appears a definite pattern. This is not too surprising, however I don't know if this has been clearly shown before.

I'm trying to attach or insert a small graph (JPEG) I made of MPG vs % Hwy, however with my lack of posting knowledge, have not had success yet. Any help??

Here's another try.......

JDL "will your statistical analysis support multiple data sets per VIN?"

Well, kind of. It would be fine and is probably a good idea to get multiple data sets over time. The only thing is that it somewhat dilutes the impact of measuring VIN as a potential MPG impacting factor.



"Another data point you might want to include, then, is the rough #miles on the vehicle at the time of the data set"

If I am interpreting your suggestion properly, I believe this information is captured in Question 9, (Miles to Date).

Thanks for the input.

It really sucks barely knowing how to use the posting capability. As you can tell, I'm a greenhorn to forumland posting.

Originally posted by norton
JDL "will your statistical analysis support multiple data sets per VIN?"
[...]
"Another data point you might want to include, then, is the rough #miles on the vehicle at the time of the data set"

If I am interpreting your suggestion properly, I believe this information is captured in Question 9, (Miles to Date).*snip* I was hoping my next sentence (you didn't quote) would have been more clear:

``Perhaps just to differentiate the sets per VIN, or track another correlation to "new car break-in".''

So I was suggesting you might use odometer readings to distiguish one data set from another for the same VIN.
I believe you can still find the VIN correlation, if it exists, from multiple data sets. In fact, more so, since you may have the same VIN with significanty varied (other) conditions.

Anyhoo, I'll hold off until you say when you'd like more data sets (per VIN)... -jd.

1. RECENT Combined City/Highway Average MPG = 19

2. % Highway Driving = 80%

3. Driving Style = B

4. VIN Number (last 6 digits) = 102274

5. Model (eg. Base, GT, etc) = GT

6. 6 speed

7. Octane (Number) of Fuel Used = 93(shell)

8. DSC/TCS = on

9. Miles to Date = 6300

10. Approx % Time Driving with Windows Open = 95%

11. Approximate % Time Driving with AC on = 5%

12. State = Florida

Originally posted by norton

I'm trying to attach or insert a small graph (JPEG) I made of MPG vs % Hwy, however with my lack of posting knowledge, have not had success yet. Any help??


Norton, you attach your .jpg file the following way:

1. Create a post. On the "Attach File:" row, click on the Browse button.
2. Select your .jpg file and click ok.
3. Submit your post.

Just make sure your .jpg is below 204k.

1. RECENT Combined City/Highway Average MPG = 21 mpg

2. % Highway Driving = 95%

3. Driving Style = A

4. VIN Number (last 6 digits) = 109161

5. Model (eg. Base, GT, etc) = GT

6. Automatic / 6 speed = 6 Sp

7. Octane (Number) of Fuel Used = 87

8. DSC/TCS = Yes

9. Miles to Date = 2500

10. Approximate % Time Driving with Windows Open = 3%

11. Approximate % Time Driving with AC on = 0%

12. State = CA

1. RECENT Combined City/Highway Average MPG = 19

2. % Highway Driving = 30%

3. Driving Style = Average

4. VIN Number = 102058

5. Model = GT

6. 6 speed

7. Octane (Number) of Fuel Used = 87

8. DSC/TCS = Yes

9. Miles to Date = 5300

10. Approximate % Time Driving with Windows Open = 10%

11. Approximate % Time Driving with AC on = 99%

12. State = CA

Downshift - Thanks for the posting tip. Hopefully it will work this time.

Once again --- I don't yet have enough observations to conduct the complete analysis, however I did notice one interesting thing while taking a quick look at the few observations so far. Looking at MPG and % Hwy, there appears a definite trend. This is not too surprising, however I don't know if this has been clearly shown before with % Hwy vs MPG. Please take a look at the graph (if I posted it correctly this time).

http://www.rx8club.com/attachment.php?attachmentid=5883&stc=1

1. 20
2. 10%
3. A
4. 113952
5. GT
6. 6spd
7. 93
8. yes
9. 440
10. 40%
11. 20%
12. FL

1. 17.68 mpg
2. 0% Highway Driving (all town)
3. A
4. 101211
5. GT
6. 6 Speed
7. 87 octane
8. DSC/TCS = Fully Disabled
9. 3737 Miles
10. 90% Windows Open
11. 10% AC on (exact info this week)
12. Florida

Average speed per mile 29 mph!!!!
(added this from info at end of thread)

1. 22
2. 85%
3. A
4. 109104
5. GT
6. Automatic
7. 92
8. DSC/TCS = Yes
9. Miles to Date = 1650
10. Approximate % Time Driving with Windows Open = 0%
11. Approximate % Time Driving with AC on = 50%
12. State = WA

FYI with 95% hiway driving I get 24+ mpg.

1. 21.0
2. 90%
3. B
4. 106429
5. GT
6. 6 speed
7. 93
8. Yes
9. 2267
10. 0%
11. 50%
12. SC

Kind of sounds like the Buckingham Pi theory...good luck...:)

1. 21
2. 80
3. A
4. 112585
5. base
6. 6 speed
7. 93
8. No DSC
9. 2000
10. 95
11. 0
12. NY - feeling blue for the Yankees

1. RECENT Combined City/Highway Average MPG = 20
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = 15

3. Driving Style = A
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = 112741
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = Base

6. Automatic / 6 speed = 6 Speed

7. Octane (Number) of Fuel Used = 93

8. DSC/TCS = No. Don't have it

9. Miles to Date = 1,571

10. Approximate % Time Driving with Windows Open = 25%

11. Approximate % Time Driving with AC on = 10%

12. State = PA
(I’ll later convert to Geographic Region)

Norton -- Yer awesome. I nominate you for immediate instatement to Sr Member for at least attempting this. I am already impressed by your graph which shows a pretty good correlation btwn hiway driving and mpg. For those data points somewhat out of the norm, I bet if you query those drivers a bit more you would find out why they're so out of whack. For instance, "Highway driving" in LA is stop and go and could equate to city driving elsewhere. Recommend you investigate more those people who don't fall near the norm in that chart.

My responses:

1. RECENT Combined City/Highway Average MPG = 16.7
2. % Highway Driving = 40
3. Driving Style = B. Average to Above Avg (I accelerate hard but almost never go above 7K rpm. Cruise below 3500 rpm.)
4. VIN Number (last 6 digits) = It's on that thread.
5. Model: GT
6. 6 speed
7. Octane (Number) of Fuel Used = 87
8. DSC/TCS = Yes (fully enabled)
9. Miles to Date = 5100
10. Approximate % Time Driving with Windows Open: 50
11. Approximate % Time Driving with AC on: 40
12. State: CA

1. 15
2. 10%
3. C (Like someone mentioned before, I drive it like I stole it).
4. 102787
5. GT
6. 6 speed
7. 91
8. DSC/TCS = off
9. Miles to Date = ~5,500
10. 30%
11. 1%
12. State = CA

For instance, "Highway driving" in LA is stop and go and could equate to city driving elsewhere.

I think stop-and-go is actually worse than city driving. When I put 95% highway I was thinking of the tanks where I avoided commute hours. Silicon Valley traffic is not much different from LA.

Originally posted by ptiemann
I think stop-and-go is actually worse than city driving. When I put 95% highway I was thinking of the tanks where I avoided commute hours. Silicon Valley traffic is not much different from LA.

Stop and go is bad, not only do you need more fuel to pull off each time, but also sitting stationary uses as much fuel as traveling at around 12mph, and you obvious aren't putting any miles on the clock.

Cheers
---Dave

Originally posted by druck
Stop and go is bad, not only do you need more fuel to pull off each time, but also sitting stationary uses as much fuel as traveling at around 12mph, and you obvious aren't putting any miles on the clock.

Exactly my point. If you say your are driving 50 percent hiway but your hiway is stop and go, might as well count it like city driving. It is assumed hiway driving is more efficient (i.e, greater miles per gallon) but clearly that is not always the case.

For instance, "Highway driving" in LA is stop and go and could equate to city driving elsewhere. Recommend you investigate more those people who don't fall near the norm in that chart.

Exactly my point. If you say your are driving 50 percent hiway but your hiway is stop and go, might as well count it like city driving. It is assumed hiway driving is more efficient (i.e, greater miles per gallon) but clearly that is not always the case.

On my 42 mile Central Jersey commute to work this morning I did a lot of pondering about this % Hwy thing. At the outset, it appears like it may be a pretty important factor impacting MPG. There are a couple shortcomings in using % Hwy numbers though. These are described as follows:

1. Per the quotes above (great observation), not all Hwy driving is the same type of driving for everyone and its not the same for an individual every time that person hits the highway. Likewise not all city driving is the same.

2. The % Hwy is an educated guess, at best a ballpark figure. It's not really an emperically measured number like odometer reading or mpg. There is bound to be some error in these estimates.

3. People may have differing interpretations as to exactly how Highway and City are defined. Thus a somewhat apples to oranges comparison among responses.

Even with these problems though, I am fairly pleased with the results so far, using % Hwy as one of the primary determining factors of MPG.

*************************************************

I do have a NEW variable I thought of, which pretty much removes the shortcomings of using % Hwy described above. Unfortunately determining this factor will be a pain, time consuming, and will take a while before you could provide it. The NEW factor is............. . Average Speed per Mile .

The good thing about using Avg Speed per Mile is that it is totally emperical. No subjective guessing involved, no different interpretations of Hwy vs City, and it pretty much "normalizes" all road conditions (eg A highway full of stop and go traffic is quite similar to city driving).

The pain in using Average Speed per Mile is in the calculation, though I will simplify it as much as possible. Basically you would need to provide a couple things:

[/B]1. # of miles traveled recently (from odometer reading).

2. The amount of time spent driving. (unfortunately this requires recording the beginning and ending time of every ride).[/B]

Average Speed Per Mile = (Total Miles / Total Minutes) * 60

This calculation should be done on the same odometer mileage as is used in calculating MPG. (Yes, unfortunately that would need to be provided again).

I'm NOT suggesting we do this right now (or even that we do it), however it is certainly something to think about. My guess is that there would be a very very strong relationship between Avg Speed/Mile and MPG.
Please let me know what your thoughts and feelings are about later pursuing the Avg Speed/Mile information. If people think its overkill or not worth it, I can understand their viewpoint.

*******************************************

For now I would like to stay focused on working with the great data I have been getting. I have begun working on the Regression Model. Due to the volatility and variation in the observations I'm receiving, the Regression results vary somewhat with each additional response. As I continue getting more observations, the results should begin to settle towards a stable conclusion.

Great response data. Please keep 'em coming. Thanks.

Too bad we don't have an hour meter for total ignition-on time. We could then just use the odometer for miles & total gas consumed (if you've been recording that, like you should if you're really recording things to compute overall mpg).

1. 20.2
2. % Highway Driving = 90
3. Driving Style = C
4. VIN Number (last 6 digits) = 103169
5. Model (eg. Base, GT, etc) = GT
6. Automatic / 6 speed = 6sp
7. Octane (Number) of Fuel Used = 93
8. DSC/TCS = Yes
9. Miles to Date = 4700
10. Approximate % Time Driving with Windows Open =0
11. Approximate % Time Driving with AC on = 50
12. State = MO

1. RECENT Combined City/Highway Average MPG = 15
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = 20%

3. Driving Style = C
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = 574
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = GT

6. Automatic / 6 speed = 6MT
7. Octane (Number) of Fuel Used = 95

8. DSC/TCS = Yes / No(Don’t Have or Fully Disabled)yes

9. Miles to Date = 800

10. Approximate % Time Driving with Windows Open = 10%___________

11. Approximate % Time Driving with AC on = _30%

12. State = wa
(I’ll later convert to Geographic Region)

1. 16.5mpg avg last 4 fill ups (with an autox)
2. 40%
3. C ++
4. 101182
5. Touring
6. 6 speed
7. 91
8. dsc off 50% time
9. 4400
10. 20%
11. 80%
12. NV

Well I have 24 observations so far. That's about the minimum I need, so I will hopefully get the initial Regression Analysis done tomorrow. Here is an updated graph depicting % Hwy vs MPG. Still shows a definite pattern.

One interesting thing to note are the two outliers which show 20 mpg, yet a low % Hwy - 10% and 15% respectively. Based on % Hwy alone, someone would probably conclude those are aberations. There is a valid reason for these two outliers though. For those two observations, the Driving Style was "A" (easy going), thus yielding a higher MPG. This is exactly the kind of situation that the Regression Analysis automatically takes into account, by simultaneously assessing multiple factors.

Can't wait to get the Regression results.

http://www.rx8club.com/attachment.php?attachmentid=5914&stc=1

Erm, hate to throw a spanner in the works at this stage, but is that % highway driving by time or by distance?

Erm, hate to throw a spanner in the works at this stage, but is that % highway driving by time or by distance?

Lurcher: Excellent catch. You've got a very valid point. Let's see now.

If someone spent only 5% of their time on the highway and drove 80% of the total combined hwy/city distance on th hwy, would we say that person has 5% hwy proportion or an 80% hwy proportion? This situation would mean that the person spent a frustrating 95% of their driving time going very little distance (20% of the combined hwy/city distance).

My view is that the % Hwy would be based on DISTANCE. The reason is that City Driving implicitly assumes more time spent going fewer miles than Hwy Driving. So I believe the time factor in the % split is already taken into consideration.

Nonetheless, you've raise a very good point about the ambiquiety in using % Hwy. I think it's an o.k. variable to use in the analysis, however Average Speed per Mile is an infinitely better measure to assess City vs Hwy driving. (Please see my comments about 7 posts up.

Keep rockin', Norton. You data and methodology seem very valid so far.

Thanks 8_wannabe. I've been following this terrific forum for close to a year always find it interesting and exciting. I would really like to help towards understanding the factors heavily impacting mpg.

Originally posted by norton
Lurcher: Excellent catch. You've got a very valid point. Let's see now.

If someone spent only 5% of their time on the highway and drove 80% of the total combined hwy/city distance on th hwy, would we say that person has 5% hwy proportion or an 80% hwy proportion? This situation would mean that the person spent a frustrating 95% of their driving time going very little distance (20% of the combined hwy/city distance).

My view is that the % Hwy would be based on DISTANCE. The reason is that City Driving implicitly assumes more time spent going fewer miles than Hwy Driving. So I believe the time factor in the % split is already taken into consideration.

Nonetheless, you've raise a very good point about the ambiquiety in using % Hwy. I think it's an o.k. variable to use in the analysis, however Average Speed per Mile is an infinitely better measure to assess City vs Hwy driving. (Please see my comments about 7 posts up.

I think it's OK as it is as long as people correct for true highway vs city highway driving. I think most people would classify stop and go rush hour traffic on a highway/freeway as city driving. If this is so then this is a non-issue. But another issue is that not all highway driving is equal. I logged a lot of highway miles today with an average speed of probably about 83, which should result in a much lower MPG than if I had gone 55. So maybe we should add an average highway speed to the matrix. Note 25 mph and 35 mph won't really matter, so we do not need an average city speed.

1. RECENT Combined City/Highway Average MPG = _15.8__________
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = __10%____

3. Driving Style = B
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = ___________
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = ____GT_______

6. Automatic / 6 speed = ____6_________

7. Octane (Number) of Fuel Used = ___93_________

8. DSC/TCS = Yes / No(Don’t Have or Fully Disabled) fully disabled when i remember

9. Miles to Date = ___1018________

10. Approximate % Time Driving with Windows Open = ____50_______

11. Approximate % Time Driving with AC on = ______5%_____

12. State = ___NJ___________
(I’ll later convert to Geographic Region)

1. RECENT Combined City/Highway Average MPG = 15.044
2. % Highway Driving =65%
3. Driving Style = C
4. VIN Number (last 6 digits) =101877
5. Model (eg. Base, GT, etc) = GT
6. Automatic / 6 speed = 6 speed
7. Octane (Number) of Fuel Used = 91
8. DSC/TCS = Yes
9. Miles to Date = 3,240M/5217km
10. Approximate % Time Driving with Windows Open = 2
11. Approximate % Time Driving with AC on = 0
12. State = Alberta, Canada

Can I mention that it would be more useful if you dealt with kilometers, liters and other than only US geography?

I also suggest to ask altitude, as it has a significant effect on fuel economy.
In my case 2,700ft/855M

Originally posted by matt
Here's another take on the issue. What if the speedo's are.."optomistic"? say 1.5 mph off. That would reduce the MPG. I think before you can establish a baseline. You need to use another method of calculation. If the speedo's are at fault, then all the data collection in the world will not show a thing.


my .02 yen
Speedos are 4% optimistic on the stock 18" wheels/tires.

I suggest you ask at what rpm do you normally shift in 1st, 2nd, 3rd.

If a person has been recording use in highway and city driving reasonably accurately it is easy to see the difference to a great degree.
Here are my stats. I live in Alberta, we have some long open highways, and most often run at around 145kmh (90mph) at around 4300rpm on the highway.

Based on my last 12 tankfuls, I had 7 of mostly or all highway and 5 of mainly or all city.

I averaged 14.43l/100km, or 16.37mpg on highway
I averaged 17.07l/100km, or 13.80mpg in city.

Originally posted by canzoomer
I suggest you ask at what rpm do you normally shift in 1st, 2nd, 3rd.

That's question 3, driving style.

I find it interesting that most people apparently think they either drive more than 80 percent highway or less than 20 percent hiway. This is a phenomenon known as a "well curve" that goes down in the middle. If it were a bell curve as I would have expected, most drivers would say they are around 50/50 hiway/city, and it would tail off at both ends of the curve.

18.9 mpg
50%
B
108393
GT
6 Speed
93 of piss poor ethanol made for smog control can't wait for the winter version
Yes
1989 mileage
0 % windows
5 % AC
ILL

Just a note mileage last 4 tanks hasn't varied more then + - .3
I had the tires at 40 psi ( first 600 miles ) didn't check the dealers work, but I was getting 21 mpg. The ride was a rough one. I am going to try 35 psi. I found my Tundra gets better mileage 2-3 mpg by running 32 psi vs the recommended 28 psi.

Average speed per mile 29 mph!!!!
(added this from info at end of thread)

RodsterinFL: That's terrific! How did you get this info so quickly. Do you have navi, and if so, is avg speed displayed??
If we could get that info (avg speed) from everyone, that would be great. I believe Avg Speed is a much better determinant of MPG than % Hwy, which is really only a ballpark estimate.

I know exactly how far my work is. I have driven there for 6 years. Basically I figured average travel time with miles traveled. The time was easy for me to figure since I look at the clock each morning and then write in my arrival time at work each day.

Seems like avg. MPH would yield the most normalized result. Trip lenght might help, as well.

VIN 108802 Recent MPG at ~5k odo = 21.1

Here's info, as requested:

1. RECENT Combined City/Highway Average MPG = 21.2
2. % Highway Driving =85%
3. Driving Style = ? econodrive w/ 2 sprints to 9k
4. VIN Number (last 6 digits) =108802
5. Model (eg. Base, GT, etc) = GT
6. Automatic / 6 speed = 6 speed
7. Octane (Number) of Fuel Used = 87
8. DSC/TCS = Yes
9. Miles to Date = 4,892
10. Approximate % Time Driving with Windows Open = 1
11. Approximate % Time Driving with AC on = 100
12. State = SoCalif

Seems like avg. MPH would yield the most normalized result.
MPG > HP: I couldn't agree with you more. The problem is obtaining it is somewhat a pain. In addition to the odometer reading, everyone would also need to record the cumulative driving time (over the same period for which they which they are also calculating MPG).
If people did this, then we would have some GREAT data to work with. If anyone is interested in pursuing Avg MPH please let me know. I would do the calculation if you provide the Cumulative Time.

Ok, anyone wanting to participate would need to follow a procedure, like this:

1. Add an "Avg MPH" column to your MPG Log. (Keep "Trip Times" on a separate scatch sheet).
2. Always log start and end times so trip times can be calculated.
2. At each fillup, add all the trip times since the last tankful and divide the total trip miles by the cumulated # of hours for Avg MPH.
3. Report your mileage and Avg MPH here.

As long as you can get good numbers for any given tankful it won't matter if you "mess up" logging for any "MPG Only" tankful. Accuracy would count more than quantity of sample points, so if you can only report MPG, that statistic would be usable, as before.

If you wanted to be really accurate, feel free to add a "Trip Miles" column. I'm sure Norton can separate out the reports of "MPG", "MPH" and "Miles Per Trip", but you would have to keep accurate per trip logs to get the benefit of really accurate numbers. This would especially show the difference between open hiway, rush hour and short city trips where the most variability is likely to occur. ("Stomp the gas" trips could be asterisked, if you really want to go crazy on this.)

I'll start logging for avg mph at the start of my next tank and see where this takes us.

1. 19.8
2. 80
3. Average,
4. 107556
5. GT
6. 6 speed
7. 89
8. Yes
9. 2950
10. 50
11. 50
12. CA

1. 17.4
2. 70
3. C
4. 100502
5. T
6. 6 speed
7. 92
8. Yes
9. 4666
10. 2%
11. 2%
12. MI

Originally posted by norton

OK, I just got my 8 two days ago. Here's the results of my first fill-up. I'll try to post new data for each fill-up (unless I'm away from my computer at the time).

1. RECENT Combined City/Highway Average MPG = 18.8
First tank. Dealer fill-up.

2. % Highway Driving = 60%
3. Driving Style = A I'm still in "break-in" mode.
A. Easy going (Don’t normally use high rpm range, only occasionally)

4. VIN Number (last 6 digits) = 107141

5. Model (eg. Base, GT, etc) = GT

6. Automatic / 6 speed = 6-Speed

7. Octane (Number) of Fuel Used = 91 (dealer-supplied)

8. DSC/TCS = Yes

9. Miles to Date = 294

10. Approximate % Time Driving with Windows Open = 0

11. Approximate % Time Driving with AC on = 2

12. State = Calif.

1. 16.45
2. 63%
3. B
4. 111534
5. GT
6. 6 speed
7. 93
8. Yes
9. 538
10. 10%
11. 60%
12. Alabama

Local conditions in city driving involves hills and many short runs with stop signs.

Hey Norton, how about an updated chart like the one you did on 10/24. You've got a lot more datapoints to include now.

I'd like to thank Norton for bringing a statistical approach to the fuel economy issue. It's always nice to see practical application of an education. :)

The RX-8 would not have made it to production if it couldn't pass the gass guzzler tax limit which is 22.5 mpg (unadjusted combined).

The results of the EPAs tests were seen briefly on Mazda's website and caused some initial high hopes. Does anybody remember what they were? :)

20.4 mpg city / 30.2 mpg highway

The EPA's numbers were actually 20.402 mpg city / 30.2244 mpg highway (23.8967 mpg combined). These EPA unadjusted figures are determined by running 2 driving schedules on dynos. To test city/urban economy, the EPA measured fuel usage on their LA-4 driving schedule (aka FTP-72, UDDS, etc). To test highway fuel economy, the EPA measured fuel usage on their Highway Fuel Ecomony Test (HWFET) driving schedule.

So how did the numbers change from 20.4/30.2 to 18/24? Sorry to proponents of conspiracy theories but www.fueleconomy.gov has the answer:

"To make the numbers in the Fuel Economy Guide more useful for consumers, EPA adjusts these laboratory test results to account for the difference between controlled laboratory conditions and actual driving on the road. The laboratory fuel economy results are adjusted downward to arrive at the estimates in the Fuel Economy Guide and on the labels seen on new cars, light trucks, and vans. The city estimate is lowered by 10% and the highway estimate by 22% from the laboratory test results. Experience has proven that these adjustments make the mileage estimates in the Fuel Economy Guide correspond more closely to the actual fuel economy realized by the average driver."

20.402 * .9 = 18.4 city mpg
30.2244 * .78 = 23.6 highway mpg

How many people here knew that that? :) The EPA verifies their above preproduction testing results on 10 - 15% of the production models.

There are many factors which can affect individual fuel economy but if anyone here doubts the EPA results, they should be able to find a certified testing center that can simulate the FTP-72 and HWFET dyno tests under federal testing conditions.

Brian

1. MPG: 18.62

2. % Highway Driving = 85

3. Driving Style = B: Average

4. VIN Number (last 6 digits) = 103488

5. Model (eg. Base, GT, etc) = GT

6. Automatic / 6 speed = 6 Speed

7. Octane (Number) of Fuel Used = 92

8. DSC/TCS = Yes

9. Miles to Date = 1700

10. Approximate % Time Driving with Windows Open = 0 %

11. Approximate % Time Driving with AC on = 80 %

12. State = Missouri

I'll try to do an update on the MPG analysis next week. Been swamped lately with my job.

I wish we had a way to track another factor... Average Temperature.

I have mentioned in another thread, but my MPG dropped by about 2MPG consistently when the average temps around here dropped from mid 60s to upper 30s (we had a sudden cold spell for 2 weeks). I went from a consistent 17 MPG down to <15 MPG (the 15 was over 2 tanks).

Interesting also is the fact that the temps are warmer now, and I can tell that my MPG is back. I haven't finished a tank yet, but during the "Bad" days, I went through 1/2 tank before I hit 100 miles, my current tank hit 1/2 at 125 miles (I am at 176 miles at 1/4 tank now, typical to my 17 MPG tanks).

I posted my data before, this time with your from.

1. RECENT Combined City/Highway Average MPG = 14.7
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = 85%

3. Driving Style = C
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = 106438

5. Model (eg. Base, GT, etc) = GT

6. Automatic / 6 speed = 6 Sp

7. Octane (Number) of Fuel Used = 89

8. DSC/TCS = Yes

9. Miles to Date = 5600
10. Approximate % Time Driving with Windows Open = 10%

11. Approximate % Time Driving with AC on = 80%

12. State = CA
(I’ll later convert to Geographic Region)

MPG went up after 2000 miles, waiting to see if gets better after the oil change at 5000 miles.
Getting low 15 MPG now after 2000 miles.

Paul

Originally posted by norton
I'll try to do an update on the MPG analysis next week. Been swamped lately with my job.

This is really valuable stuff, especially for all the RX-8 owners now trying to make a case for compensation with Mazda.

I would gladly PAY for a copy of your analysis, with info on how to do the calculations you have done.

Thanks and keep up the GREAT work!

I have a loaner while waiting for my car and have run only a few miles but I will report the basic info anyways. I drove 177 miles since yesterday, about 80 hwy at 75mph, the rest fairly aggressive in town.

1. 17.2 mpg
2. 50%
3. B-C (its a loaner :)
4. 103803
5. GT
6. 6 spd
7. 93
8. yes
9. 3200
10. 0
11. 0
12. Ky, temp in lower 40's

1. 14.1
2. 5%
3. B (it's winter)
4. 116546
5. GT
6. 6 spd
7. 92
8. yes
9. 1,588
10. 0
11. 0
12. Washington, Temps ranging between 20-41 f

1. 13.5 mpg
2. 10%
3. B.
4. 106064
5. Touring
6. 6 Speed
7. 91
8. Yes
9. 2,400
10. 0%
11. 0% (it's 20 degrees now!)
12. PA

Moderator, should this be a sticky??

Great info here

I've been out of the loop for a while....... swamped with my job lately. I see that we've gotten quite a few additional respondents since I first did the regression analysis, and will provide an update either later this week or early next week.

I will show these results of this analysis on the other similar thread, titled Results of Statistical Analysis Approach.

Boy, I've really been out of the loop. I didn't realize there was a separate results thread. Read all about it here (http://www.rx8club.com/showthread.php?s=&threadid=13404&perpage=15&pagenumber=1) in case you also missed it.

I look forward to updated data plots and reading about the statistics underlying this whole thing.

bump

This looks like an enlightening statistical analysis of the MPG issue. See also the link given by "8_wannabe" above.

Another factor that may affect MPG is cold-short drives. A good discussion about the relationship between MPG and cold-short drives is here:
http://www.rx8club.com/showthread.php?s=&threadid=15404&perpage=15&highlight=mileage&pagenumber=2
( RX-8 Forum > General Topics > RX-8 Discussion > My current MPG, the saga continues......)

Starting with "pp13bnos" at 11-28-2003 08:01 PM

One interpretation is that for cold-short drives the engine isn't warm, is driving with the "choke" on, and getting lower MPG than it would if it were warm.

Everything here makes perfect sense. I know this is premature and unscientific, but my guess is there isn't a fuel economy problem necessarilly. The rotary engine (Even the Renesis) is not very efficient outside certain ranges. It's amazing how many people are getting close to or above 20mpg though (combined no less). These figures really resemble the posted numbers from Mazda. If you drove it like you stole it, you're outside the range: please don't be amongst the disappointed.
Average ambient temps and trip duration are the missing vital stats as pointed out by Trx8. I have concluded; again prematurely and unscientifically, that 8s driven in low enough temps for relatively short distances will get similar figures to the pedal to the metal crowd: end of mystery.
Can they improve it? Probably.
If you hadn't noticed, I'm rather opinionated. I apollagise.
Great thread norton.

for me short trips kill the mpg. and i think more so now in winter. ive noticed that my mileage is reduced by 1 to 3 mpg when i take short trips out for lunch. i mean like just a mile or 2 so the engine barely has time to warm up. just 2 lunches out per week seems to be enough. if i eat in or walk and drive the same route to and from work 1 get 17 to 18. just 2 trips for lunch will drop it to 15-16.

In the MPG statistical analysis I conducted several months ago, several variables were explored:
- Percent Highway
- Driving Style
- VIN
- Octane
- Region (State)
- Model
- Auto vs 6-Speed
- Windows (% time open)
- AC (% time on)

The only ones significantly impacting MPG were Percent Hwy and Driving style. Based on the data and analysis, I came up with the following estimate of MPG using Driving Style and % Hwy as determinants:

After conducting the analysis, it seems that one factor in particular continues to get mentioned as likely impacting MPG. This is average length of trip (i.e. impact of many cold starts vs few cold starts - since the RX-8 evidently runs quite rich when cold). Unfortunately, I never included this factor originally when I requested inputs from owners.

If there is much interest, I would be happy to redo the entire analysis to now include "# of cold starts" &/or "average length of trip". We could then assess the true impact of this variable on MPG. Unfortunately, even if it does impact MPG a lot, there isn't much each owner can do to change this factor.

Please let me know if you're interested. Then I'll set up a thread for inputting the data.

Originally posted by norton

The only ones significantly impacting MPG were Percent Hwy and Driving style. Based on the data and analysis, I came up with the following estimate of MPG using Driving Style and % Hwy as determinants:

I dispute this. On highway driving the most significant variable is speed.

At 45mph I get 22mpg
At 60mph I get 18.5mpg
At 85mph I get 15.9mpg
At 110mph I get 12.9mpg.

This is based on actual highway trips.

Yes, there IS a road not far from here you can drive about 150 miles at 110mph. Goof thing there is a gas station at the halfway point.

The simple fact is that if one lived in Europe, and used this car on the Autobahn or similar high speed national highways it might not be affordable to drive.

Here in Alberta, where the accepted speed on major highways is around 135 to 150kmh ( 83 to 93mph) I get some pretty awful milage, averaging around 15.8mpg

It's nice to drive, though!

Norton, I think your analysis is right on. It fits with everything I've seen and read on this forum. Thank you for all your hard work on this.

Canzoomer's mileages seem a little low for the respective mph (not counting the 45 mph one) during highway cruising.

And what's up with the high mileage for 45 mph? Are you in 5th or 6th gear?

"I dispute this. On highway driving the most significant variable is speed.

At 45mph I get 22mpg
At 60mph I get 18.5mpg
At 85mph I get 15.9mpg
At 110mph I get 12.9mpg.

This is based on actual highway trips."

Canzoomer: Others have made this same observation as you - that greater highway speeds have a decreasing impact on MPG. I agree with you. When I was saying "The only ones [factors]significantly impacting MPG were Percent Hwy and Driving style", I also said, "Based on the data and analysis". What I meant was those two factors were the ONLY ones impacting MPG of those variables I collected. If I had collected "Hwy Speed" this too would have likely had a significant impact on MPG. Unfortunately, those variable (as well as other potentially impacting variables) were not included.

We need to be realistic about interpreting the results of norton's regression analysis. The usefulness of the results are bounded by the inputs and the underlying model. Its common to find cases that are out-of-bounds, and some of them have been listed above. In those cases, interpretation of the results need to be tempered by the conditions that norton has been careful to qualify.

In my opinion, norton did an exceptional job of:
- Creating the idea of using a regression analysis
- Setting up the model
- Soliciting input
- Inputting and tabulating raw data from the forum
- Cranking the numbers
- Interpreting, posting, and explaining results

His results are good and usable, they are given as:
- Tabulated raw data
- Regression output
- Simplified algebraic model
- Tabular form based on the two dominant factors
- Running discussion
- Likely things I missed

I know some of my driving is out of bounds (cold-short drives). From what he has reported, I have derived a better basic understanding of my MPG situation, and what to do about it.

norton -- thanks for the very useful results

You're welcome Trx8.
Before I started the analysis, I was really hoping to find one or two things that people could actually control to significantly improve their mileage. Unfortunately, from the data provided I only found "% Hwy" and "Driving Style" as impacting MPG. Things like % Hwy are pretty much a given for each person; that is a way of life for them determined by the area they live in, their commute, etc. They don't really have the ability to change % Hwy. People can impact their MPG by easing up on their driving style, but that kind of goes contrary to what the car was intended for.
Basically, as others have stated, it appears to me that the RX-8 overall reacts similar to many other cars to things that impact MPG (e.g. short trips, many cold starts, hwy speed, hard accelaration, etc). It just seems that the RX-8 is just FAR MORE sensitive to these factors.

This thread has given me more peace of mind about my '8 than any other. Before your analysis, I woulda sworn my car was defective and needed some kind of ECU fix. But based on my highway percent + driving style, I see I am right smack on your distribution curve. I could get better mileage if I tried, but I don't feel like trying. Thanks, Norton.

You're welcome, 8_wannabe.
I am a prospective RX-8 owner, considering for the future. If I had a shorter commute to work, I myself would not be so concerned with the mileage issue. However with a 42 mile commute EACH way, MPG becomes a consideration at some point -- both from a cost perspective and also having to refill every couple days. Luckily, the bulk of my commute (95%) is Hwy. Unfortunately, this Hwy driving is N.J. Hwy, which is a lot of stop and go, and creeping and crawling, combined with 80 mph sprints.

Therein lies the weakness in your poll: Highway does not always equal highway. Stop 'n go don't count.

Therein lies the weakness in your poll: Highway does not always equal highway. Stop 'n go don't count.
I know. You are right. That's why a while back I had proposed also incorporating "Average Speed". This would have gotten around the weakness you've noted above, however it was not easy to calculate.

Originally posted by norton ...
I know this MPG topic has been beaten to death, and I apologize for bringing it up again, however I would like to propose a new approach to understanding this MPG issue.

THANKS FOR TAKING THE TIME TO RUN SOME FIGURES!!!
hope this helps ...

1. RECENT Combined City/Highway Average MPG = last tank:
12.8 mpg (and pissing me off PLENTY!!!)

2. % Highway Driving = 25%

3. Driving Style = B

4. VIN Number (last 6 digits) = 109611

5. Model (eg. Base, GT, etc) = touring (not GT though)

6. Automatic / 6 speed = 6 (of course!!! ;)

7. Octane (Number) of Fuel Used = 91

8. DSC/TCS = Yes / No(Don’t Have or Fully Disabled) almost always on

9. Miles to Date = 1600

10. Approximate % Time Driving with Windows Open = 20%

11. Approximate % Time Driving with AC on = <5%

Wow man, those actual mpg you guys are getting is pretty bad, that's about as bad as driving around in an automatic GTO - LOL. I guess you guys who are waiting for the '05 model for whatever reason are getting nervous about being hit with a gas guzzlers tax if the feds re-evaluate the RX-8 again.

- Mike

1. 15.1
2. 20%
3. B
4. 111524
5. touring
6. 6 speed
7. 93
8. yes
9. 1577
10. 0%
11. 0%
12. MD

Originally posted by norton
You're welcome, 8_wannabe.
I am a prospective RX-8 owner, considering for the future. If I had a shorter commute to work, I myself would not be so concerned with the mileage issue. However with a 42 mile commute EACH way, MPG becomes a consideration at some point -- both from a cost perspective and also having to refill every couple days. Luckily, the bulk of my commute (95%) is Hwy. Unfortunately, this Hwy driving is N.J. Hwy, which is a lot of stop and go, and creeping and crawling, combined with 80 mph sprints.

I also have a long commute (50+ miles each way) in NJ. Virtually all of my driving is along Rt78 into Jersey City. The creeping and crawling combined with the 80 mph sprints equal out to around 19 MPG consistantly. The best I've done is a bit over 20, the worst a bit under 18. Manual transmission, just under 4000 miles. It's subpar mileage, but it's manageable. I like the 8 enough that the extra 3-5 MPG I'd get in a comparable car are a worthwhile sacrifice.

Hope that helps a bit.

1. 18.32
2. 60
3. B
4.
5. GT
6. 6 speed
7. 93
8. Yes
9. 1196
10. 0
11. 10
12. FL

RECENT Combined City/Highway Average MPG = 14.85
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = 20%

3. Driving Style = B
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = 119291
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = GT Loaded no Nav

6. Automatic / 6 speed = Auto
7. Octane (Number) of Fuel Used = 93

8. DSC/TCS = Yes

9. Miles to Date = 883

10. Approximate % Time Driving with Windows Open = 0%

11. Approximate % Time Driving with AC on = 0%

12. State = NJ

(I’ll later convert to Geographic Region)

Just wanted to let "future data contributors" know, I won't be adding any more observations to the analysis. After obtaining around 30 observations, I found that the results really did not change much. If people still wish to contribute their info though, please do so. Maybe someone else could put the data to good use.

I also have a long commute (50+ miles each way) in NJ. Virtually all of my driving is along Rt78 into Jersey City. The creeping and crawling combined with the 80 mph sprints equal out to around 19 MPG consistantly. The best I've done is a bit over 20, the worst a bit under 18. Manual transmission, just under 4000 miles.

MMGDC: This is a BIG help. Thanks. Sounds like you and I start from the same area (around Clinton??). Half my commute is 78W also, then up 287N to Parsippany. So if my Driving Style is similar to yours, I should expect similar MPG.

So, MMGDC, would you categorize your Driving Style as Easy, Average, or Hard?

Oops, 78E to 287N, not 78W.

Yes, I live around the Clinton area, so our commutes should correspond pretty well. I haven't taken 287N during rush hour in a long time, and have no idea how the traffic flows, so you may find yourself doing more heavy traffic than me. I find that most of my stop n go is on 78E before I reach 287, with another chunk near the end of my commute in Jersey City.

My driving style is probably somewhere between easy and moderate. I go 80 when the traffic is moving, but the fastest I've ever had the car is 90 or so. I try to redline once a day just to give the rotary a workout, but otherwise I rarely get the RPMs much past 5 or 6K. FWIW, I haven't really noticed much mileage variation from driving style. It's all about the highway miles and taking long trips as opposed to a bunch of short hops. Also, the car positively guzzles gas when idling.

Still, unless you spend a lot of time on 287 sitting in bumper to bumper traffic, there's no reason you shouldn't get at least 18 MPG. Hope this helps you decide!

1. 12.9 mpg
2. 10%
3. B
4.
5. GT
6. 6 speed
7. 93
8. yes
9. 1900
10. 10%
11. 5%
12. VA
don't have my vin on me will update at a later time

1. 19.5 mpg
2. 90% (5% stop and go)
3. A
4. 118328
5. Touring
6. 6 speed
7. 89
8. yes
9. 1500
10. 60%
11. 1%
12. CA

1. 19.5 mpg
2. 90% (5% stop and go)
3. A
4. 118328
5. Touring
6. 6 speed
7. 89
8. yes
9. 1500
10. 60%
11. 1%
12. CA

Not sure if this thread is still gathering data- - here is mine anyway
1) 14
2) 10%
3) b
4) 131558
5) Sports pack
6) Automatic
7) 93
8) Yes
9) 7500
10) 0
11) 30
12) MA

Just a comparison on MPG with a different vehicle. We just recently bought an 8 that my wife drives and have not been through a full tank yet, so no data there. But, I drive an 05' Nissan Altima 3.5L 250 HP V6. Estimate MPG 20 city, 30 Hwy. Adding and subtracting from the estimated MPG, here are some things I have noticed:
- All city driving, stop and go: Subtract 4 MPG = 16mpg
- 50% stop and go 50% expressway - 0 = 20mpg
- 25% stop and go 75% expressway - +2mpg = 22mpg
- Heavy acceleration at stop or passing - -2 to 4 mpg

- Hiway driving
- 55 to 60 mph - 0 = 30mpg
- 61 to 69 mph - -2 = 28mpg
- 70 to 79 mph - -3 = 27mpg
- 80 + - -5 = 25mpg
- head wind 5 to 10 mph - -1mpg
- head wind 11 to 19 mph - -3mpg
- head wind 20 to 29 mph - -5mpg
- head wind over 30 mph - -7mpg
- Tail wind 5 to 15 mph - +2
- Tail wind 16 to 25 mph - +3
- Tail wind 26 + - +4

So, if I am traveling on the hiway at 73mph with a 25mph head wind, I can expect about 20mpg. I drove last weekend about 150 miles east on the interstate with about a 25 to 30mph headwind both coming and going with rain and averaged 21mpg. The car has a built in mpg calculator in the trip meter and is very accurate. When I bought the car I was thinking that if I am on the highway, I should get close to 30mpg, but later learned that it all depends on the way I drive, wind, hills, road surface and how fast I am going. I imagine the same theory holds true with the 8.
I like the Altima, has plenty of power and looks OK for a 4-door. I would still rather drive my wife's 8 though. What a sweet car.

1. 11.5 mpg

2. % Highway Driving = 0%

3. Driving Style = B

4. VIN Number (last 6 digits) = 159627

5. Model (eg. Base, GT, etc) = Grand Touring

6. Automatic / 6 speed = 6 speed

7. Octane (Number) of Fuel Used = 87

8. DSC/TCS = Yes

9. Miles to Date = 1200

10. Approximate % Time Driving with Windows Open = 0%

11. Approximate % Time Driving with AC on = 0%

12. Chicag IL

1. RECENT Combined City/Highway Average MPG = __17_________
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = __40___

3. Driving Style =
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = __136395_________
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = ___GT ________

6. Automatic / 6 speed = ____6SPD_________

7. Octane (Number) of Fuel Used = ___93_________

8. DSC/TCS = Yes
9. Miles to Date = ____20896_______

10. Approximate % Time Driving with Windows Open = __0__(WINTER) _______

11. Approximate % Time Driving with AC on = ____0

12. State = VA
(I’ll later convert to Geographic Region)

Sample is 3368 miles recorded Dec 2005 to March 2006. Average temp was right around freezing.

1. RECENT Combined City/Highway Average MPG = ___17.06________
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = _60%_____

3. Driving Style = B
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = __135795_________
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = __GT_________

6. Automatic / 6 speed = ___6 mt__________

7. Octane (Number) of Fuel Used = ___91____(winter gas)_____

8. DSC/TCS = Yes / No(Don’t Have or Fully Disabled)

9. Miles to Date = __17K_________

10. Approximate % Time Driving with Windows Open = __0__(too cold)______

11. Approximate % Time Driving with AC on = ___0________

12. State = __Toronto, Ontario, Canada____________
(I’ll later convert to Geographic Region)

1. RECENT Combined City/Highway Average MPG = _16
(Calculated Correctly and One Number please, not a range)

2. % Highway Driving = _10%

3. Driving Style = C
A. Easy going (Don’t normally use high rpm range, only occasionally)
B. Average,
C. Above Avg (Use Upper RPM range quite often and accelerate hard)

4. VIN Number (last 6 digits) = 137665
(NOTE: If you already entered your VIN on the thread “Let's compare VIN numbers and fuel economy”, I can get it from that thread).

5. Model (eg. Base, GT, etc) = Sport package

6. Automatic / 6 speed = 6-speed

7. Octane (Number) of Fuel Used = 91 (always)

8. DSC/TCS = Yes / No(Don’t Have or Fully Disabled) DSC/TCS always ON

9. Miles to Date = 8200

10. Approximate % Time Driving with Windows Open = 5%

11. Approximate % Time Driving with AC on = 15%

12. State = CALIF
(I’ll later convert to Geographic Region)


1.3L