Bet that title got your attention! I'm one of the folks who was getting average 13-14 mpg in my 8 in around town driving. I didn't complain about it (much), but it secretly drove me nuts that other people were consistently getting 18-20 mpg in the same type of driving (not to mention that the EPA estimated mileage on the window sticker said I should!)

Well, I did something and now I'm consistently getting about 18 mpg in the same driving I was getting 13-14 with before! What I did will probably seem quite obvious to many of you, but it was a revelation to me!

So step right up and hear my secret: I learned how to drive a 6-speed! No, I don't mean working the clutch and accelerator and shifting gears; I've been doing that for 20 years (since I first started driving). I just learned WHEN to shift. I've never owned a 6-speed before -- all the manual transmissions I've ever driven were 4- or 5-speed (well there was that 3-speed on the steering column truck I drove a couple of times when I worked at a grocery store when I was 17, but I digress...)

In a 5-speed, 5th gear is the "overdrive" gear that you never use except on the interstate. In a 6-speed, that place is taken by 6th.
Similarly, in a 5-speed, around town driving is usually in 3rd. It follows that in a 6-speed (at least this one), you can easily row your way up to 4th around town. I was driving with the RPM's too high by staying in 3rd most of the time (because the 3rd gear in the RX-8 is so damn "tall").

As a result of this "shift" in my driving habits, I'm getting about 5 more miles per gallon! Eventually, my new shifting pattern will become second nature to me, and I won't have to continually remind myself to upshift to 4th.

Like I said, this is probably extremely obvious to many people, but it was something new I had to learn.

i found out something 2. i unpluged my battery and reset the ecu, well i now have my results. I have increased my mpg by 3 instead of 16-17 i have receved 19-20 i reached 270 miles with 2 gallons left over OMG. I have always shifted at

1-2 2800rpms
2-3 3000rpms
3-4 3000rpms
4-5 2800rpms
5-6 3000rpms

and on highway i dont go over 82 tahst about 4100-4300rpms for about 45 miles a day.

Great suggestion. Thanks for taking the time to post it.

Originally posted by eclps0
i found out something 2. i unpluged my battery and reset the ecu, well i now have my results. I have increased my mpg by 3 instead of 16-17 i have receved 19-20 i reached 270 miles with 2 gallons left over OMG. I have always shifted at

1-2 2800rpms
2-3 3000rpms
3-4 3000rpms
4-5 2800rpms
5-6 3000rpms

and on highway i dont go over 82 tahst about 4100-4300rpms for about 45 miles a day.

hmm so you think resetting the ECU had this affect?

i think it does i have always used shell gas since day one same pump same gas station. Shifted teh same the same everything except the ecu being reseted.

i gave up shifting at certain points. it has had little affect on my MPG. so i wind it up any chance i get. thats what this engine wants.

eclps0, I shift about like you, maybe a couple hundred rpm higher. Maybe I'll try that unplug-the-battery trick. I consistently get 16.5 mpg no matter what I do or how I drive. How many tankfuls have you gone thru since pulling this trick? Did u change your driving habits?

first tank 19.4 mpg
second tank 20.6mpg
Third tank dont know yet just filled up about an hour ago

if i do mostly highway i can break 20 easily. how many miles on your 8 eclps0? has your city/highway driving changed?

I drive alot in ft Lauderdale, la solas, and riverfront where its bumper to bumper traffic. I also drive on I 75-595 to get to school.

I get about 21 MPG with 60/40 hiway/city. I routinely shift at 3500 RPM or lower going from one gear up to the next. On a trip from Las Vegas to San Diego I got 25.1 MPG but I never went over 70 MPH. The harder you accelerate the more gas you waste because Mazda is going to make your engine run fuel rich so you don't burn it up. To me it is just as much fun to reach 85 mph by sneaking up on it as flooring it to get there.

If you want to get to 85 mph fast then quit complaining about your MPG. If you don't mind taking a little while to get there--enjoy that sweet sound of the wind being louder than your engine:-)

Or you could drive like me. I shift at redline, and keep going until I hit the speed limit (usually second gear) then shift into 5th or 6th. Mileage sucks, but its fun getting there. (12-14 mpg)

Are people with ATs getting bad mileage? I've been getting a consistent 18-19 mpg.

Originally posted by Charleston
I get about 21 MPG with 60/40 hiway/city. I routinely shift at 3500 RPM or lower going from one gear up to the next. On a trip from Las Vegas to San Diego I got 25.1 MPG but I never went over 70 MPH. The harder you accelerate the more gas you waste because Mazda is going to make your engine run fuel rich so you don't burn it up. To me it is just as much fun to reach 85 mph by sneaking up on it as flooring it to get there.

If you want to get to 85 mph fast then quit complaining about your MPG. If you don't mind taking a little while to get there--enjoy that sweet sound of the wind being louder than your engine:-)


Charleston If u were talking to me this is directed to you if u weren’t talking to me than don’t read what is below.
.
.
.
Ok if your reading this u directed your comments about me whining, well where in this post was I ever whining about the gas mileage? Ok so before u say something about me or assume how I acted or reacted towards my mpg. Know the facts!!!




P.s I posted my findings for people that were worried about mpg.

I know that I am averaging about 14-15 mpg now and when I first brought my baby home it was more like 9-10 mpg. She only had 7.5 miles on her that night and now she has 1600. I drive conservatively about 50% of the time. The best gas milage I have been able to acheive has been on the highway at about 19 mpg.

Has anyone had any success taking their car back to the dealer on this matter?

Y'all are making me cry! For those who shift below 4K, please consider selling your car to someone who can truly appreciate a rotary engine :). Seriously, if you don't ever take your 8 into the upper RPM range, you aren't treating it nicely. My own motto: "A redline a day keeps the mechanic away" :D

Rotaries need to be driven - don't baby them for the sake of gas mileage. You'll regret it in the long run. Besides, it really shouldn't affect your mileage much at all. The mileage suffers mainly due to stop-and-go rush hour driving, when you're mostly at idle. Winding it up to 70MPH with a couple of redlines will not affect your mileage much at all - I do it at least twice a day, and I still get 18-20MPG.

Khoney, you might be right. I have babied my car for about 20 tankfuls, getting a high of 22.65 and a low of 18.68. My average is between 20.5 and 21.0. My lower mileage tanks seemed to happen whenever I got caught in traffic or city stop-and-go at any appreciable amounts (even a little bit of stop-and-go seems to pull the mileage down significantly).

I'm finally satisfied that I probably don't have a mileage lemon, so beginning with my current tank of gas, I'm testing if being more liberal with the gas pedal (lots of semi-hard acceleration, shifting at 5000-6000 rpm instead of 3000-4000 rpm) and average speed will have an appreciable effect. I don't want to speak too soon, but so far it looks like it won't pull the mileage down very much.

I'll report when I get results.

I may have the strangest habit of all. I wind 1st and second out and shift directly into 6th. I rarely ever use 4 or 5. I use 3rd alot but when I want to accelerate I just cant justify rowing through all those gears when just a couple will do. You are already at the legal limit after 2nd anyway. I get 18 mpg. average.

Greg, I do that a lot too, when I'm on roads that allow it. 2nd gets me up to cruising speed, and when I hit redline I just pop over to 6.

I was one of the ones getting really good gas mileage to begin with, and now my mileage is getting worse. why? Because I drive the hell out of the car now. As someone else said, I know I can get the mileage if I want it, so I'm just having fun now. The current tankful is looking the worst so far- I've got 90 miles on half a tank!! I usually get at LEAST 130 miles before it hits the halfway mark.

Originally posted by eclps0
i think it does i have always used shell gas since day one same pump same gas station. Shifted teh same the same everything except the ecu being reseted.

I don't know where Davie is.. but here in Clearwater it's been cooler than normal. Does air temp affect gas mileage?

Hey eclps0;

Have you noticed any difference in the car's performance? I was going to try this over the weekend, but thought "ehh, something so simple as disconnecting the battery for 12 hours couldn't possibly make a difference!"

Did you follow any specific procedure when driving the car afterward so the computer would "relearn" in a certain way?

My mpg has improved a little....From 12 mpg to 15.3mpg. The car has about 1400 miles on it now. I put midgrade gas in it. I am hoping it will get closer to 18 mog someday. How are the automatics gas mileage compared to the stick shift cars? Anyone with auto's out there with good or bad mpg?

Well guys my milage is slowly coming up too. It use to be right around 13-14mpg, but has increased to 18mpg. I'm also driving the car alot harder, wich is kina odd.:confused: Best tank was a little over 25mpg. CJ

Figured I would add my 2 cents in here. I have gotten perhaps the largest range of MPG of anyone on the boards now :)

As I posted in another thread, I had a 23+ mpg tank on a weekend spent doing almost 100% highway driving.

Well, since the weather turned cold here in Atlanta, my last tank of 100% city driving was beyond miserable. In stop and go traffic for most of the tank, I managed a paltry 168.1 miles on 13.29 gallons. If you run a quick calculation, that is less than 13 mpg! (12.65 to be exact). Now, I know my car isn't a lemon or I wouldn't be able to get great gas mileage on the highway when I need it.

Which means there has to be another explanation. I always knew that the stop and go driving in city would make the mileage worse, but I seriously believe that the weather has had a large effect too. Consider that over the exact same route a couple of months ago in warmer weather with a tank of 100% city, I got in the range of 16 mpg. That's a fairly large variation. The motto? Let your engine warm up, and avoid stop and go traffic!

Originally posted by khoney
Y'all are making me cry! For those who shift below 4K, please consider selling your car to someone who can truly appreciate a rotary engine :). Seriously, if you don't ever take your 8 into the upper RPM range, you aren't treating it nicely. My own motto: "A redline a day keeps the mechanic away" :D

Rotaries need to be driven - don't baby them for the sake of gas mileage. You'll regret it in the long run. Besides, it really shouldn't affect your mileage much at all. The mileage suffers mainly due to stop-and-go rush hour driving, when you're mostly at idle. Winding it up to 70MPH with a couple of redlines will not affect your mileage much at all - I do it at least twice a day, and I still get 18-20MPG.

Just for the record, my original post wasn't about shifting at low RPMs, it was about using 4th gear where I'd use 3rd on a 5-speed. I generally do shift around 5000 rpm, and I redline it whenever I have the opportunity!

I drive mine like I stole it....redline whenever I can. After starting out pretty dismal (about 14 MPG), I'm getting about 17-18 MPG in town and 22MPG-24 MPG all interstate (except when some "doofus" challenges me and I have to run up to 100 MPH +) with 3K+ miles on the odo.

Since winter has hit, those numbers have dropped again. I do believe it has more to do with "reformulated winter fuel" than anything else, though.

jtimbck2,
Thanks for clarifying and getting back to your origianl topic. However, I'm not sure what you mean by driving in 4th when you normally dirve in 3rd with a 5 speed.
I too have been driving 5 speed manuals for nearly 20 years and am trying to understand. For those times when I don't feel the need to travel quickly, I like to focus on gas milage. Especially the mundane travel to and from work.
So, jtimbck2, can you give me an mph reading when you would shift to 4th? Your right, 3rd is quite tall. Did you shift to 4th at 35......42mph to achieve better results?
Thanks
Al

Do you lose all the waypoints on the navigation if you disconnect the battery? I drive 95% highway and am averaging just a tad over 17 mpg @78-85 mph. It doesnt seem to matter if i use 87,89, or 92 octane. That seems like an easy trick, but if the dealer flashed the computer, would it do the same thing?

Eric

Originally posted by 80CuIn
jtimbck2,
Thanks for clarifying and getting back to your origianl topic. However, I'm not sure what you mean by driving in 4th when you normally dirve in 3rd with a 5 speed.
I too have been driving 5 speed manuals for nearly 20 years and am trying to understand. For those times when I don't feel the need to travel quickly, I like to focus on gas milage. Especially the mundane travel to and from work.
So, jtimbck2, can you give me an mph reading when you would shift to 4th? Your right, 3rd is quite tall. Did you shift to 4th at 35......42mph to achieve better results?
Thanks
Al

Every transmission is different; but I'm just generally talking about around town driving (in the approx. 35-45 mph range). With a 5-speed, I'd rarely shift up to 4th for those kinds of speeds; I'd just drive in 3rd. Which is what I'd been doing in the 8 because it's so smooth. I've started using 4th for that general speed range in most cases. The result has been improved gas mileage.

Simple? Yes. Obvious? Not necessarily, especially to someone who hasn't driven a 6-speed before now.

Heh -- my 500th post :-)

From reading all the threads and posts on gas mileage it appears that 3 factors affect it the most; driving style, gas quality and outside temperature. The outside temperature most likely is also affecting gas quality since I believe gas companies switch their summer gas for winter gas which is formulated differently for colder climates. I live in Southern California so we don't get the winter temp extremes here but I know back east they use different gas in winter. It doesn't seem to matter which car you drive or whether it's MT or AT.

I'm surprised at the posts that report shifting at 3k or lower shift points. If you look at a dyno graph of the power/torque curve of the Renesis engine you'll see that's a very inefficient point to be shifting. Keeping the rpms low WHILE trying to accelerate is going to cost you gas mileage...period. It's almost like lugging the engine because you're forcing it to use fuel to try and gain power since the rpm's are so low.

The optimum shift point on the graphs I saw show it to be around 5,300 rpm. That's the point where the torque and horsepower curves cross. That will give you the most torque and power the engine can deliver at the same time. If you wind it up to higher rpms you gain horsepower but lose torque. This is something you would do when you're already at speed and have mass-in-motion so top speed is now the goal rather than getting up to speed. Good for track racing obviously. Street racing is different since it's all about acceleration. If you want a maximum performance shift for acceleration in a race, shift at about 5,800-6,000 rpm so that in the next gear the rpm's START at the maximum peak torque for the next gear. Torque is what pushes mass forward. That will kick your car forward the quickest until you reach 4th gear; once you're heading for 5th gear now you can wind it out on the tach because mass is in motion and you're going for top end speed.

Around town I normally shift at about 4,500 rpm if I go by sound instead of looking at the tach so that's generally where I shift if I'm just driving regularly without pushing for performance. I always shift for performance when getting on the freeway. My gas mileage even at worst is about 18mpg. Best mileage under normal driving is around 21. BUT...again I live in Southern California where the temps aren't as cold and we don't have the winter gas that's sold back east.

To those of you shifting at 3k or lower...try shifting at 4,500 rpm as a test for one tank of gas. Your engine won't be working as hard to accelerate the car because the rotating mass of the engine is providing power instead of just using fuel. All else being equal you should see an improvement in engine temps and performance. You can still accelerate gently if you like but wait until you hit 4,500 rpm before shifting; you'll definitely notice the improvement in "kick" when you shift to the next gear. Believe it or not the engine will use less gas getting you up to speed this way.

I can't say what effect the winter gas has on mileage since we don't use it here where I live. But I bet you should at least see SOME improvement in mileage with a more efficient use of engine power and torque while shifting.

jtimbck2,
I'll give it a shot. I'll try driving in 4th at around the 35-45mpg range (speed for most of my commute) as well and see.
If it works, great, if not, well, it was an easy test. Trying to be optimistic.
Al

Originally posted by Ole Spiff

The optimum shift point on the graphs I saw show it to be around 5,300 rpm. That's the point where the torque and horsepower curves cross.

Just a FYI. Horsepower is Torque * RPM divided by 5252 so the lines will always cross at 5252 RPM on every dyno chart.

short shifting can help gas milage if you avoid those extra fuel ports opening up and pouring in tons of gas. My GSL-SE got great milage if I shifted before ~3000 RPM becuase it kept some of the ports closed. After 3000 you could feel the power increase as the fuel gauge raced from right to left. ;)

Winter gas always makes for worse gas mileage. This might be what some are atributting to colder weather.


When I had mu WRX, I noticed something similar to what those of you that have reset your ECU have noticed. After re-setting, the car gave improved mileage and felt more responsive. In the case of the WRX, the ECU will advance or retard the ignition timing depending on the knock sensor activity and the way you drive. It "learns" what conditions of all sensors are more suceptible for knocking and retards the ignition and adds more fuel to keep things safe. Sometimes, it would learn the wrong thing and think that this everyday normal way you drive is a condition that is suceptible to knocking, so it keeps the mix rich and the timing retarded.
Re-setting the ECU clears that "learned behavior" and lets it start again.

I'll try driving in 4th at around the 35-45mpg range...

Someone posted this above. IMHO lowest rpm+least amount of throttle applied=optimum gas mileage. Leave 3rd and 4th out of it unless you need the power to pass someone or to accelerate quickly. 6th is my "go to" gear ALWAYS. After acceleration put it in 6th and leave it there regardless of speed. (unless the engine seems like it is under heavy load i.e. <30 mph. My mileage has always been consistently around 18.

Originally posted by Charleston
I get about 21 MPG with 60/40 hiway/city. I routinely shift at 3500 RPM or lower going from one gear up to the next. On a trip from Las Vegas to San Diego I got 25.1 MPG but I never went over 70 MPH. The harder you accelerate the more gas you waste because Mazda is going to make your engine run fuel rich so you don't burn it up.

To me it is just as much fun to reach 85 mph by sneaking up on it as flooring it to get there.
Whether I shift at 3000 or 6000, it has no affect on my gas mileage. I average around 19.5 mpg.

I disagree with your second point. For me, it's all about acceleration/handling. Speed is not as important. I enjoy getting to 65 -70 mph as quick as possible. Then, hit the cruise control. I rarely drive over 70 mph, anyway. But that's just me.

I also believe that cruising speed has more of an impact on gas mileage than acceleration or shift points. At least, that's what I have experienced so for after putting 4500 miles on the car.

Originally posted by Keshav
Just a FYI. Horsepower is Torque * RPM divided by 5252 so the lines will always cross at 5252 RPM on every dyno chart.


Really? Where did this come from? So, a Ford F-350, with a torque of 350 @ 2500 RPM needs only 166 HP (350 * 2500) / 5252. Yet, it has 260 HP. Wonder what the other 100 HP is for.

Torque is a "rotating force: force that causes rotation, twisting, or turning, for example, the force generated by an internal-combustion engine to turn a vehicle’s drive shaft".

As a good example, let's use human strength. If you apply it to a standard screwdriver, you can tighten to about 8 foot pounds. Now, use some leverage with a socket wrench... and the foot pound force us humans are capable of is directly related to the lenght of the wrench. A torque wrench is usually greater than 15" long, giving one the ability to apply 60 foot pounds or more.

In a piston engine, the arm length of the crank shaft (offset from center position) provides the leverage. A rotary on the other hand... I'll leave that to the experts.

Originally posted by Zeltar
Really? Where did this come from? So, a Ford F-350, with a torque of 350 @ 2500 RPM needs only 166 HP (350 * 2500) / 5252. Yet, it has 260 HP. Wonder what the other 100 HP is for.



Really that is the correct formula. what you have shown, if your math is correct i didn't check, is that at 2500rpm that truck is only making 166hp but you don't have the final drive ratio, so you can't tell what it's making to the wheels. the T in a rotory is made by rotors gears turning the Eshaft.

Originally posted by zoom44
Really that is the correct formula. what you have shown, if your math is correct i didn't check, is that at 2500rpm that truck is only making 166hp but you don't have the final drive ratio, so you can't tell what it's making to the wheels. the T in a rotory is made by rotors gears turning the Eshaft.

Zoom44, you have a good point. Max torque is not usually at the same point as max HP. That's frustrating. You might actually know what you're talking about. :)

Originally posted by Zeltar
Really? Where did this come from? So, a Ford F-350, with a torque of 350 @ 2500 RPM needs only 166 HP (350 * 2500) / 5252. Yet, it has 260 HP. Wonder what the other 100 HP is for.

Torque is a "rotating force: force that causes rotation, twisting, or turning, for example, the force generated by an internal-combustion engine to turn a vehicle’s drive shaft".

As a good example, let's use human strength. If you apply it to a standard screwdriver, you can tighten to about 8 foot pounds. Now, use some leverage with a socket wrench... and the foot pound force us humans are capable of is directly related to the lenght of the wrench. A torque wrench is usually greater than 15" long, giving one the ability to apply 60 foot pounds or more.

In a piston engine, the arm length of the crank shaft (offset from center position) provides the leverage. A rotary on the other hand... I'll leave that to the experts. Max HP is NEVER at max. torque, it's practically impossible. So, yes, you've calculated the HP at the rpm's where you get max. torque. I wish you gave the rpm's at 260 max. HP. If you use 260 for max hp & the rpm's at that max hp as "n", you can calculate the torque @ max hp by using T=hp*5252/n You will then see that torque @ 260max hp is less than 350 max torque @ 2500rpm.

So, yes, it's really true. HP = T*n/5252 (lb-ft torque.)

Torque is not a force. It's more like a bending moment, except it's around a center, twisting. Torque = force * distance, like a bending moment of a beam. That's why it's given in lb-ft. Force in lbs. - distance in ft. lb-ft , or, ft-lb , pretty much the same difference.

Your example of a screwdriver is complex actually. The muscles in your arm act to twist your hand, torquing it, acting against the torque of the screw, thru the screwdriver. This is a muscular thing inside of your arm, controlled by your brain. Certain muscles actual produce the forces which creat the torque around where you want the center of rotation to be (the screwdriver).

Your 15" long torque wrench is a good example. The longer it is, the less force from you is required to produce the same amount of torque. And visa-versa.

Your crankshaft is another classic. The "offset from center position" is the distance, the force from combustion, pushing the piston down, or the rotor around, is the force. Actually, it's all very dynamic & the forces required to suck the intake in & compress the fuel/air mix just prior to combustion & push the exhaust out, from the other cylinders, or rotary chambers, subtract from the "net" torque coming out of the crankshaft. Yeah, best left to the experts...:D

I also believe that cruising speed has more of an impact on gas mileage than acceleration or shift points. At least, that's what I have experienced so for after putting 4500 miles on the car.

Agreed. After 7,500 miles this is what I have concluded as well.

Of course, I do not get involved with much stop-and-go city driving that might skew my results.

Avg 20-22 mpg.

Originally posted by rxeightr
Agreed. After 7,500 miles this is what I have concluded as well.

Of course, I do not get involved with much stop-and-go city driving that might skew my results.

Avg 20-22 mpg.

i have 10,000 miles and i finaly broke 20 mpg with babing the crap out of her. why cant i get better mpg.

Originally posted by Zeltar
Really? Where did this come from?

I acquiesce to the torque formula. Found this website which has many interesting auto related formulas:

http://www.prestage.com/Car+Math/Car+Math+Formulas/default.aspx

Thought you may be interested.

Ole Spiff, what you say about torque curve seems to be consistent with what I'm seeing. My current tank I'm shifting between 5000 and 6000 rpm and I'm not seeing too much of a dropoff in mileage, at least so far. I'll continue to test this hypothesis.

Glad to hear you're experimenting shift_zoom8. It's a crying shame to have a wonderful car like this which is such a blast to drive, and be driving it like a granny buick to try and get gas mileage. Like I've said, I shift at around 4,500 rpm or a little more as an average, I do NOT baby the car for mileage, and I use 87 octane regular gas. I drive 50/50 street/highway and I just got 256 miles on a 13.1 gallon fill-up. The car is running great and I'm looking forward to crossing the 9,600 mile mark on the odometer to see if the ECU change will make things even better. I have 7,600 miles on it now.

Something that somebody else posted I agree with which is cruising speed affects mileage. When on the street I'm usually in 5th gear once I'm up to speed; 6th gear if I'm over 50mph. I can always downshift if I need to accelerate quickly.

The main thing to remember is your car is a mass of about 3,000 lbs (plus you, whatever you weigh). It takes power to move that mass. Combustion engines convert exploding fuel into rotating motion which, through gearing, creates torque which drives your vehicle forward through tires contacting the ground. Basic stuff. To learn to drive your car efficiently, you need to use the gearing to take advantage of the flywheel effect in the engine so you use the least amount of fuel and still get good performance.

Wind and road contact friction generate the resistance that is always trying to slow down your car. You overcome this with a combination of fuel usage and gearing. Gearing is free, fuel isn't. Use fuel and gear shifts to get that mass in motion until you reach a steady-state speed; then use the lowest gear you have to maintain that speed. Wonder how Corvettes get 30mpg on the freeway? At freeway speeds in 6th gear the rpms are about 2,500.

When coming to a complete stop don't downshift; put it in neutral and use the brakes. Not only will that help gas mileage but brake pads are cheaper to replace than clutches and transmissions.

Efficient use of the gear ratios and rpms will get you the best mileage you can while still enjoying the performance of a great car like this.

I concur, Ole Spiff. From what you wrote, our driving styles seem to be identical. I get 18mpg normally, 21 on a trip. It got a tad better since new. I have some 3,300 miles on her so far...still a baby.

A fuel mpg monitor would be very interesting to have. With no fuel return line, I would think that it would have been a piece of cake to add a monitor.

OK, I have an AT with about 2350 miles and am seeing 15 to 18 mpg (mostly on the 15 side for stop & go - the 18 was on a day trip with all highway driving). A mechanic at the dealership told me he wouldn't even look at it until I hit 37k miles, cause he hasn't found anything to do to the cars he's seen to up the mileage. Others' experience with ATs?

I have the automatic too...dealer said don't worry about it until you at least have 5000 miles on it. Then a gentleman around 60 ish at the gas station noticed my car and started chatting with me about it.....I mentioned gas mileage was bad and he said I may not see it get better until I have anywhere from 12,000-24,000 miles on it. He seemed to know something about the rotary engine. So we shall see....that seems like a long wait but I bet we will get there in no time! I think weather has a lot to do with it...cold ,damp conditions and breaking it in....my theories from a person who knows squat about rotaries!:]

Arggghhhhhh! If you bought the car for fuel economy, trade it for a Toyota Prius. It's a sports car, for Pete's sake. The author of the initial post has not learned how to drive a 6 speed. If you buy a car with 6 gears, there is a reason. The reason is not to slowly creep up on 70 mph. It's to make it scream. I agree that first and second gears are all that are needed to make it to sixth gear. However, that being said, third gear is a lot of fun, too. It's a good passing gear on the interstate. Third gear is kinda like a seven iron (if you golf).

Originally posted by XLR8
Arggghhhhhh! If you bought the car for fuel economy, trade it for a Toyota Prius. It's a sports car, for Pete's sake. The author of the initial post has not learned how to drive a 6 speed. If you buy a car with 6 gears, there is a reason. The reason is not to slowly creep up on 70 mph. It's to make it scream. I agree that first and second gears are all that are needed to make it to sixth gear. However, that being said, third gear is a lot of fun, too. It's a good passing gear on the interstate. Third gear is kinda like a seven iron (if you golf).

If the sticker on the car said 15 MPG I wouldn't complain
but it said 18 to 24

Originally posted by XLR8
Arggghhhhhh! If you bought the car for fuel economy, trade it for a Toyota Prius. It's a sports car, for Pete's sake. The author of the initial post has not learned how to drive a 6 speed. If you buy a car with 6 gears, there is a reason. The reason is not to slowly creep up on 70 mph. It's to make it scream. I agree that first and second gears are all that are needed to make it to sixth gear. However, that being said, third gear is a lot of fun, too. It's a good passing gear on the interstate. Third gear is kinda like a seven iron (if you golf).

It's not about getting the fuel economy of a Prius or not. It is about all the hype of the Renesis being such an improvement in all areas, INCLUDING fuel economy, over the previous 13B.
It is about getting a fuel economy that goes along with the power and performance of the car. About meeting the expectations.

If the expectation, as presented by Mazda, is that the car is supposed to give an average mpg of 21 mpg, then it is reasonable for people to expect to get something close to that number if they want to.

You sound like the people that say that the RX-8 can't be a real sports car because it has 4 doors and more than 2 seats.

Another thing to keep an eye on is tire pressure. Keep the tire pressures at the recommended (32psi) or a pound or two higher to get better gas mileage. Low tire pressures will cause a lower gas mileage because of the increased friction on the roadway. This will be particularly an issue in cold climates where the tires may not heat up properly in short commutes. Make SURE your tires are at 32psi minimum when cold.

A lot of things can affect overall mileage, including rear wings. While wings may look "cool" keep in mind why they're used in racing. It has nothing to do with looking cool. It's for generating downforce on the tires at high speeds to increase traction and grip. They DO slow down the car and they DO cost gas mileage as a result. This is a necessary trade-off in racing to get higher cornering speeds but it costs tire wear and gas to do it.

On the street you can't go fast enough safely to gain the benefit of those kind of racing body modifications. All those racing body attachments people put on their cars are costing them the same things it costs racers on the track; tire wear and fuel usage.

IF you have a rear wing on your car and if it's adjustable, set it to a neutral angle to minimize drag. You really can't go fast enough on the street to take advantage of the downforce in cornering; it's just for show. The front spoiler (which I bought for mine and it looks great) may have some benefit at freeway speeds because it helps reduce undercarriage drag by keeping air from getting under the car, but without hard testing data that's just a guess on my part. Reducing undercarriage drag is partly what they're for on race cars...that and providing downforce for the front tires to match the downforce on the rear tires.

Every add-on adds weight; weight means it takes more gas to move that body mass. Keep all this in mind before you load down your car with tons of add-ons and heavy speakers and such.

The RX8 DOES get the mileage they advertise IF you follow their standard testing procedures and configs for the car. I consistently get 19-20 mpg and I definitely enjoy the performance of this great machine. Anything you do that adds weight or increases drag and downforce will cost you mileage in return; nothing is free in this area.

It's not Mazda's fault. It's the US Govt (and other Govts) fault. They mandate a certain fleet average for MPG, then they separatly mandate emissions. The two can be unrelated. Then the Govt (US at least) mandates CAT lives. Now the three are unrelated, but are interrelated. So Mazda, complies with the fleet average (I have no idea how, but assume they do), then to comply with emission and cat life, they dump tons of unburnt fuel to the cats to cool the cats down to prolong life. Note this does not effect emissions because the cats do a great job of converting unburnt fuel into co2 and h2o, but this greatly lowers mpg. So what does Mazda do? They print a manual with ridiculous shift points. The epa has it's hands tied and tests the motor at those shift points and issues the city/hwy mpg estimates that are posted on the sticker. The problem is nobody will shift at those points! Mazda was smart, they designed a gret car with a lot of potential at high rpms and met federal standards by not making use of the high rpms. Any fault lies with the US govt's way of estimating mpgs.

Too many Italian cars in my past -- couldn't dream of regularly shifting a car anywhere shy of 1000K from redline unless I was starting off on ice.

I note that the engine makes some strange sounds when it's running < 3000 RPM. Unhealthy sounds.

The ride is jerky at low RPMs as well. Slight variations in throttle really jerk the car about. Bad news here with the rolling landscape. Could it be the carbon fiber driveshaft?

Nah, it 's your right foot. ;)

For those of you who think you are doing your car a favor and shifting at low RPMs, you are hurting it more than helping. By shifting at low RPMs and never getting it to redline, the Rotary engine builds up a lot of carbon. Over time this leads to higher compression numbers, which can then lead to possible clogs or blown seals. Redlining the engine helps clear out this carbon buildup....but if you never redline it for 20,000 miles, don't expect to immediately start dislodging this carbon buildup by redlining...the damage has been done.

Be easy on it through the break in stage, but once complete, like someone else said "redline a day, keeps the mechanic away"...

If you have a rotary and are shifting at 3500 rpms, it is a shame. Go trade it in for a piston engine.

Happy Rotoring!

Kurt G.

Originally posted by cruzdreamer
I have the automatic too...dealer said don't worry about it until you at least have 5000 miles on it. Then a gentleman around 60 ish at the gas station noticed my car and started chatting with me about it.....I mentioned gas mileage was bad and he said I may not see it get better until I have anywhere from 12,000-24,000 miles on it. He seemed to know something about the rotary engine. So we shall see....that seems like a long wait but I bet we will get there in no time! I think weather has a lot to do with it...cold ,damp conditions and breaking it in....my theories from a person who knows squat about rotaries!:]

well if thats the case everybody would be getting bad mileage from the start and MPG would get better between 12000-24000 miles but that is not the case. some people are getting good mileage from the start. but is it because they are driving more highway than city?

Some of you suggested to reset the ECU to achieve better gas milage. How do you do that? I am assuming you disconnect the battery. How long do you need to keep it disconnected? Please advise...Thanks

Mark

I've heard disconnect for 12 hours

Is there a better way to reset the ECU than waiting for 12 hours. Why 12 hours?


Mark

You don't need to wait 12 hours. Disconnect one of the battery terminals and step on the brake pedal for a couple of seconds to discharge any charged capacitor in the electrical system.

Originally posted by Genshie
For those of you who think you are doing your car a favor and shifting at low RPMs, you are hurting it more than helping. By shifting at low RPMs and never getting it to redline, the Rotary engine builds up a lot of carbon.


Is this something that you heard or something that you can actually show proof that this is the case?

Its an old rotary proverb thats generally known to be true.

Originally posted by O.R.A.
It's not about getting the fuel economy of a Prius or not. It is about all the hype of the Renesis being such an improvement in all areas, INCLUDING fuel economy, over the previous 13B.
It is about getting a fuel economy that goes along with the power and performance of the car. About meeting the expectations.

If the expectation, as presented by Mazda, is that the car is supposed to give an average mpg of 21 mpg, then it is reasonable for people to expect to get something close to that number if they want to.

You sound like the people that say that the RX-8 can't be a real sports car because it has 4 doors and more than 2 seats.

Dude, I see your point, but you've got me all wrong. Obviously, I love my 8. Of course it's a real sports car. What I'm saying is that it IS a sports car. Yeah, there are expections & numbers on the sticker, but the difference between 18 mpg and 15 mpg isn't huge. 18 might be possible. And others have mentioned factors that affect it, such as shift points, tire pressure, etc. But what I'm saying is that 18 isn't great itself. Plus, if you drive it like a non-sports car to achieve 18, you should buy the Prius.

The Prius comment is weak.

18 mpg is no big deal if that's what was expected.

However, when Mazda engineers touted the Renesis as having much improved fuel economy... that's where the rub is. It doesn't sound like anyone is seeing it.

The rotary is just as thirsty (if not more so) as ever.

Wow, people shifting at 2800-3000 RPMs?? Man, I wouldn't even consider shifting until 4500. I go by feel, but I looked today to see when I shift - and I shift around 5500. I mean the redline is 8500 and max torque at 5500. Mileage smileage....

You know, one thing I find funny is how there are a lot of people that post something like "I don't know why I get such bad mileage. I always shift at X rpms and all I get is Y mpg..."

Well, if shifting at X rpms is only getting you Y mpg, maybe you should try something else. You can't do the same thing over and over and expect a different result, even if it worked on some other car you had before.

Also, throttle position plays a big part in fuel consumption too. If you need to go at 60% throttle because of the low power available at 3000 rpms, this might not be better in terms of fuel economy than running at 30% throttle at 5000 rpms.

Does anyone know what the official city and hwy mileage for the 3rd generation RX7 was supposed to be (what was on the manufacturer's sticker)? And what were the ranges people were actually getting on the RX7 city and hwy?

Originally posted by racerdave
The Prius comment is weak.

18 mpg is no big deal if that's what was expected.

However, when Mazda engineers touted the Renesis as having much improved fuel economy... that's where the rub is. It doesn't sound like anyone is seeing it.

The rotary is just as thirsty (if not more so) as ever.

You are weak. What are the odds that the individual vehicles are responsible for the wide variation in reported mpg? Not very good. Thus, the answer is with the individual drivers & conditions. The car is capable of whatever results have been posted in this forum hundreds of times. If so, and you're that worried about 2 mpg, change your driving habits or spend a lot of time trying to figure out what the difference is. I, on the other hand, will be driving around in my 8 with a big smile on my face, not looking at my trip odo trying to figure out when I should shift. Get over it. Hop to a thread that celebrates the car & get some tips for how to get more out of the car. Dude!

Dude... still doesn't address how the Renesis was "supposed" to be better on fuel.

That's where my only issue with Mazda is...

Originally posted by aussie77

Which means there has to be another explanation. I always knew that the stop and go driving in city would make the mileage worse, but I seriously believe that the weather has had a large effect too. Consider that over the exact same route a couple of months ago in warmer weather with a tank of 100% city, I got in the range of 16 mpg. That's a fairly large variation. The motto? Let your engine warm up, and avoid stop and go traffic!

I live in Edmonton Alberta.
Got my car in the summer ( I believe first private delivery in Canada.)

It is damned cold here in winter.
Tonight for example going down to 14F.
Have had some nights down to -5 already.

I get the sme mileage now as I got in the summer.

No, wait, I get BETTER mileage, as I learned that 1-3-5th gear shifting and keeping under 3500rpm really does help.

One thing else I know:
Sitting at idle, warming up, it uses exactly the same amount f fuel as driving on the highway at 60mph/100kmh.

So, only warm it up until the rpm drops to 1500, then drive it gently until it drops to the lower idle speed.

My $.02 worth on the subject.

if i read another post about gas mileage, i will have to drown myself in the stuff. Not that valid points haven't been made, but there are only so many times you can hear someone list their mpg and when they shift gears.

i haven't bought my 8 yet since i'm a law student for a few more months (buying it in May with my starting bonus), so i've been tooling around town in a corolla (exciting stuff, i know). i have a rather heavy foot and an a/t (unfortunately) so i don't get the best mileage, but the one thing that i have noticed that makes a difference no matter what the driving style is air pressure in the tires, like someone commented on earlier.

This is probably ridiculouly obvious, but the lower the pressure, the more friction and the worse the gas mileage. For every drop of 10 degrees F, your tires will lose about 1 psi in pressure. Thus, a drop in 40-50 degrees in the winter (depending on where you live) will drop your tire pressure by about 4-5 psi. (once your tires warm up somewhat, this variance will not be as extreme)

This may not seem like much, but it can have a big effect. Last year, during the winter, I noticed that my Corolla was only getting about 26 mpg (50/50 city/highway), which by 8 standards seems like a fantasy, but by corolla standards is pretty abismal. I added about 5 psi to my tires while filling up, and the next tank of gas gave me an immediate improvement to around 32 mpg.

Now, i'm sure that with the kind of attention that 8 owners give to their cars, this isn't that big of a factor, but i thought that i'd mention it since i'm sure it contributes somewhat to the worse winter mileage that people have been mentioning. i know i'm sure as heck not worried about my tire pressure, when it's 30 degrees out (or worse). From test driving the 8, I also know that when i get mine, I'll be putting that nice big tach to work, once i've broken it in.

I was just at the dealership this afternoon and was told that I shouldn't expect to see my fuel economy go up to where the EPA reported until I get 5-7k on the odometer. They also informed me that it is oxygenated gas in WA. state that contributes to my poor fuel economy. I filled my tank in Idaho where they don't have this regulation and we will see how I do. So far so good. This oxygenation is supposed to help with emissions in the winter??? Anybody else heard of this? I don't want my dealer blowing smoke up my ass.

Originally posted by eclps0
i found out something 2. i unpluged my battery and reset the ecu, well i now have my results. I have increased my mpg by 3 instead of 16-17 i have receved 19-20 i reached 270 miles with 2 gallons left over OMG. I have always shifted at

1-2 2800rpms
2-3 3000rpms
3-4 3000rpms
4-5 2800rpms
5-6 3000rpms

and on highway i dont go over 82 tahst about 4100-4300rpms for about 45 miles a day.


you have way more self control then I do......I just got mine and it is killing me that I can't let this thing rip yet......this car just begs for more........Maybe after I get my gas bill I will have a little more self control............maybe?????

Originally posted by still w8ting
if i read another post about gas mileage, i will have to drown myself in the stuff. Not that valid points haven't been made, but there are only so many times you can hear someone list their mpg and when they shift gears.

i haven't bought my 8 yet since i'm a law student for a few more months (buying it in May with my starting bonus), so i've been tooling around town in a corolla (exciting stuff, i know). i have a rather heavy foot and an a/t (unfortunately) so i don't get the best mileage, but the one thing that i have noticed that makes a difference no matter what the driving style is air pressure in the tires, like someone commented on earlier.

This is probably ridiculouly obvious, but the lower the pressure, the more friction and the worse the gas mileage. For every drop of 10 degrees F, your tires will lose about 1 psi in pressure. Thus, a drop in 40-50 degrees in the winter (depending on where you live) will drop your tire pressure by about 4-5 psi. (once your tires warm up somewhat, this variance will not be as extreme)

This may not seem like much, but it can have a big effect. Last year, during the winter, I noticed that my Corolla was only getting about 26 mpg (50/50 city/highway), which by 8 standards seems like a fantasy, but by corolla standards is pretty abismal. I added about 5 psi to my tires while filling up, and the next tank of gas gave me an immediate improvement to around 32 mpg.

Now, i'm sure that with the kind of attention that 8 owners give to their cars, this isn't that big of a factor, but i thought that i'd mention it since i'm sure it contributes somewhat to the worse winter mileage that people have been mentioning. i know i'm sure as heck not worried about my tire pressure, when it's 30 degrees out (or worse). From test driving the 8, I also know that when i get mine, I'll be putting that nice big tach to work, once i've broken it in.

Now your my kind of driver....the break in will be a very dificult time for you as it is me.....but don't give in to temptation give the 8 time to get those seals nice and tight and you will be rewarded down the road.