Notices
RX-8 Discussion General discussion about the RX-8 that doesn't fit in one of the specialty forums.

Dramatically improved RX-8 fuel economy

Old 12-10-2003, 09:38 PM
  #51  
Registered User
 
Ole Spiff's Avatar
 
Join Date: Oct 2003
Location: Inland Empire, SoCalif
Posts: 382
Likes: 0
Received 0 Likes on 0 Posts
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.
Ole Spiff is offline  
Old 12-10-2003, 09:53 PM
  #52  
Registered User
 
Join Date: Jul 2003
Location: NC
Posts: 911
Likes: 0
Received 0 Likes on 0 Posts
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.
red_rx8_red_int is offline  
Old 12-10-2003, 10:15 PM
  #53  
Registered User
 
thered1996's Avatar
 
Join Date: Nov 2003
Location: Marietta, GA
Posts: 92
Likes: 0
Received 0 Likes on 0 Posts
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?
thered1996 is offline  
Old 12-10-2003, 10:22 PM
  #54  
Coming thru in waves...
 
Racer X-8's Avatar
 
Join Date: Jun 2003
Location: Somewhere between Yesterday and Tomorrow.
Posts: 1,488
Likes: 0
Received 0 Likes on 0 Posts
Nah, it 's your right foot.
Racer X-8 is offline  
Old 12-11-2003, 12:33 AM
  #55  
Registered User
 
Join Date: Nov 2003
Location: Campbell, CA
Posts: 25
Likes: 0
Received 0 Likes on 0 Posts
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.
Genshie is offline  
Old 12-11-2003, 12:42 AM
  #56  
Super Moderator
 
RX-GR8's Avatar
 
Join Date: Aug 2003
Location: Cherry Hill, NJ
Posts: 3,098
Received 3 Likes on 2 Posts
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?
RX-GR8 is offline  
Old 12-11-2003, 01:24 AM
  #57  
Registered
 
mqandil's Avatar
 
Join Date: Nov 2003
Location: Vancouver, WA
Posts: 166
Likes: 0
Received 0 Likes on 0 Posts
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
mqandil is offline  
Old 12-11-2003, 02:21 AM
  #58  
100% Italian
 
mikeb's Avatar
 
Join Date: Jul 2003
Location: orange,ca
Posts: 9,422
Likes: 0
Received 0 Likes on 0 Posts
I've heard disconnect for 12 hours
mikeb is offline  
Old 12-11-2003, 02:55 AM
  #59  
Registered
 
mqandil's Avatar
 
Join Date: Nov 2003
Location: Vancouver, WA
Posts: 166
Likes: 0
Received 0 Likes on 0 Posts
Is there a better way to reset the ECU than waiting for 12 hours. Why 12 hours?


Mark
mqandil is offline  
Old 12-11-2003, 01:37 PM
  #60  
Registered User
 
Join Date: Aug 2003
Location: GA
Posts: 110
Likes: 0
Received 0 Likes on 0 Posts
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.
O.R.A. is offline  
Old 12-11-2003, 01:38 PM
  #61  
Registered User
 
Join Date: Aug 2003
Location: GA
Posts: 110
Likes: 0
Received 0 Likes on 0 Posts
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?
O.R.A. is offline  
Old 12-11-2003, 03:01 PM
  #62  
Registered User
 
Greg's Avatar
 
Join Date: Sep 2003
Location: Savannah, GA
Posts: 109
Likes: 0
Received 0 Likes on 0 Posts
Its an old rotary proverb thats generally known to be true.
Greg is offline  
Old 12-11-2003, 07:37 PM
  #63  
Registered User
 
Join Date: Dec 2003
Location: Charleston, WV
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Unhappy

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.
XLR8 is offline  
Old 12-11-2003, 08:15 PM
  #64  
F125er/Future RX-8er
 
racerdave's Avatar
 
Join Date: Jul 2003
Location: WI, USA
Posts: 396
Likes: 0
Received 0 Likes on 0 Posts
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.
racerdave is offline  
Old 12-11-2003, 09:00 PM
  #65  
Registered User
 
Join Date: Dec 2003
Location: Atlanta
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
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....
SinTil8 is offline  
Old 12-12-2003, 07:17 AM
  #66  
Registered User
 
Join Date: Aug 2003
Location: GA
Posts: 110
Likes: 0
Received 0 Likes on 0 Posts
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.
O.R.A. is offline  
Old 12-12-2003, 07:36 AM
  #67  
Registered User
 
Join Date: Oct 2003
Posts: 188
Likes: 0
Received 0 Likes on 0 Posts
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?
shift_zoom8 is offline  
Old 12-14-2003, 03:45 PM
  #68  
Registered User
 
Join Date: Dec 2003
Location: Charleston, WV
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
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!
XLR8 is offline  
Old 12-15-2003, 08:01 AM
  #69  
F125er/Future RX-8er
 
racerdave's Avatar
 
Join Date: Jul 2003
Location: WI, USA
Posts: 396
Likes: 0
Received 0 Likes on 0 Posts
Dude... still doesn't address how the Renesis was "supposed" to be better on fuel.

That's where my only issue with Mazda is...
racerdave is offline  
Old 12-16-2003, 03:00 AM
  #70  
Forum Vendor
 
canzoomer's Avatar
 
Join Date: Jul 2003
Location: Edmonton, Alberta
Posts: 1,223
Likes: 0
Received 0 Likes on 0 Posts
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.
canzoomer is offline  
Old 12-16-2003, 05:07 AM
  #71  
Registered User
 
Join Date: Dec 2003
Location: Dallas, Texas
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
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.
still w8ting is offline  
Old 12-16-2003, 05:51 PM
  #72  
The Stickinator
 
93rdcurrent's Avatar
 
Join Date: Nov 2003
Location: Portland, OR.
Posts: 1,328
Likes: 0
Received 0 Likes on 0 Posts
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 ***.
93rdcurrent is offline  
Old 12-16-2003, 11:39 PM
  #73  
Registered User
 
Join Date: Dec 2003
Location: San Diego
Posts: 12
Likes: 0
Received 0 Likes on 0 Posts
Re: cool

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?????
joejoe is offline  
Old 12-16-2003, 11:43 PM
  #74  
Registered User
 
Join Date: Dec 2003
Location: San Diego
Posts: 12
Likes: 0
Received 0 Likes on 0 Posts
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.
joejoe is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Mr. Pockets
RX-8 Racing
12
12-10-2015 10:51 AM
tigg.z
New Member Forum
0
08-26-2015 09:51 PM
harithac
New Member Forum
15
08-26-2015 09:24 AM
Lee_1420
New Member Forum
1
08-10-2015 01:05 PM


Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:
You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Dramatically improved RX-8 fuel economy


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.