i've got about 30,000 miles on my car and i've had it for 4 months and i've never gotten anything bette than 18mpg and i got 12mph once too.

i drive on backroads about 90% of the time though...

 

put really big tires on your car.

use the stock rims, but put 225/70/18 on there. it will effectively increase your gear ratio and drop your rpms.

only downside is that you will accelerate slower.

 

if you're not getting at least 16mpg in mixed driving WITH the occasional redline, and obeying all traffic laws including speed limits, you dont know how to drive.

before i sold my 8 i regularly got 24mpg in mixed driving, and the occasional highway trip to Austin. my tank lasted me AT LEAST 260 miles, and a consistent 300-310 per tank if i wasn't heavy on the throttle.

all with a bone stock '04 RX-8 with 45k miles when i bought her. i sold it and bought and FD RX-7.

the WORST i got was 9mpg when i take her to autoX's and road courses.

 

you could always try running water!! it's a hellova lot cheaper.

DISCLAIMER
*I am not responsible for any problems which may occur if you try this solution*

 

right. i'll take that great insult from someone on the internet.

anyway, can anyone do the math on my mpg... 14.5 gallons lasted me 171.5 miles

 

and like someone else said.. i don't mind the fuel economy .. IF its normal.

i knew about the fuel economy BEFORE buying the car.

i'm not to sure 12mpg with a mix of city and highway driving is normal though.

 

if you live in texas or a southern state that dosen't experience snow... 12 mpg is shitty... if you live in a state where you do have a winter and cold temps, 12 isnt bad at all... when i had my 8 in its first winter(Minnesota).. i only got 8- 12 mpg if i let it warm up all the way like you are supposed to.. i got about 15 if i let it warm up just alittle bit..
and it also depends how far you have to drvie when you let it warm up... i drove mine in 15 mile chunks.. so it wouldnt go that far compared to the warm up period.. now if you drive 50+ miles in a trip.. your mpg will be alot better... due to less warm up time...

 

I usually get about 14 mpg in these winter months. Car takes longer to warm up than usual, so yeah. Then again, that's all city driving.

 

Xmas miracle - I broke 21MPG again after a long time not hitting that magic number. Mostly highway.

 

you aren't supposed to warm it up like that.. it's the same as any engine in that regard.

you turn the car on, let it settle down a bit for 2-3 minutes and go.. you don't have to sit in the car for 20 minutes till the water temp needle begins to move.. you're wasting loads of gas doing that.

obviously you don't push the car at all until you're completely warmed up and secondly use your own discretion based on your ambient situation.

 

[QUOTE=alz0rz;2790477]you aren't supposed to warm it up like that..QUOTE]

so you are telling me that this little informational dvd i got direct from mazda is lying to me??

IM 100% sure it says to let it warm up to operating temperature before driving...

and operating temp is when the temp neddle dosen't move any more at idle rpm... am i right or am i wrong here??

BUT

It also says. If you dont have enough time or the trip is short enough, you dont need to wait until its at operating temp... just dont rev past (3k??) rpms... not to sure about the 3k and i seem to have missed placed the dvd... so call me a lier i guess..

I could go on longer but why waste my breath... Information is out there, it just takes a couple of clicks and some time to figure it out...

 

Hi I am considering to buy one, but do we have to wait until it is warm and how long? how can I download this informational dvd, if it is so I may not buy because I can't leave the car alone in the city to warm up , I have to stay inside...

 

If you have the time to sit 20 minutes in your car waiting for it to warm up, go ahead. But the idea is to not put any strain on the car while it's warming up, so driving carefully after you get going, gearing at low rpms is what logics tell you.

My manual doesn't say that, so who cares what some dvd tell you, there are far more important things to consider when taking care of your car.

 

Just set a new record: over 23 mpg NYC to Exeter, NH. Nearly all highway, 60-70mph, with a strong, steady tailwind the whole way.

Starting/warming up the 8 is pretty much the same as any other car: start it up, let it run a minute, and go. Then just don't rev high 'til the engine warms up, which takes, what… 4 minutes? Good advice for starting any car.

 

I allow the engine to warm about a minute before I leave. In my daily commute, the first 3 or 4 traffic lights are improperly timed for me, so I do little more that idle the engine (in 2nd gear) to the first light and travel about 35 mph (in a 45 limit) to the next two. By the time I get to the expressway, the water temps are up and I can give it more right peddle.

 

I let mine get nice and warm before driving. Mostly because the on-ramp is right next to my house and I like driving like an ******* on it. Plus without risking tickets its the only place I can give it its needed redline a day

 

My check engine light came on when I went upstate over christmas weekend. Took it to the dealer this week and they told me that my cat had died and I got a new one. My car only has 4,000 miles on it so that is a bit surprising. I have never flooded the car, always warm it up, etc etc.

Anyway I had been getting really poor mpg in 100% city driving. There was a tank where I got 10mpg when I first got the car.

Hopefully the new cat will increase my mpg...... :D

 

In this case it is big number divided by little number: 171.5/14.5 which equals a palty 11.827 m/g.

Since I do a lot more city driving these days I am only getting 14-16. When I jumped on the free/highway I'd regularly get 20-21.

But regardless of mpg, I still get a week's worth of stuff done per fill-up.

 

/\ lol, thanks for doing the math for me 2 months later..

yes I knew that btw!!

i too make sure my tank lasts me a week.. be it going out, work, whatever..

 

That's what I get for not coming around often enough!

 

Has anyone recorded gas mileage after modifications? What does a free flowing exhaust do for the mpg, or a Green Air filter? Combine both and what happens?

Also, does the Cobb Access Port or Racing Beat computer reprograms do anything in the way of gas mileage?

Obviously a supercharger or turbo kit will reduce gas mileage because of the greater amount of fuel needed to achieve the HP, but I would like to believe that some of the exhaust and intake mods would increase fuel mileage because it is making the engine more efficient by adding a little HP without using more fuel. I would imagine that deleting the cat would make a big difference as well.

I plan on doing a test on all of these theories with our 07 RX-8, I am currently in the phase of recording the average mpg from daily driving in stock form. My wife daily drives it (spare the insults) as it was her car we traded in to get the 8, her normal commute is around 18 miles round trip to work and back, and 90% of it is 60 mph driving (the road is laced with cops). She works at a bank and has to idle the car for quite a while when she waits for her colleagues to open the store (some bank rule), so I know there is significant idle time on the car. I take the car once or twice a week to work, which is 60 miles round trip, with the 60 miles being about 30% highway and 70% city. I drive the car hard, as I am a racer and cannot help it. I heel toe downshift at stoplights, turns, exit ramps, and anywhere I feel it is necessary. I do not, however, take off at stoplights because the law enforcement is on full alert here in central Florida with street racing. I have gotten an invitation to court before for racing because I had a loud Mustang GT and the cop was retarded. So I don't race off lights because I don't trust them.
Our average mpg have been in the 19-21.5 range, with the high being a weekend trip to Sebring which is a lot of 60 mph highway. The mileage to a tank ranges from 266-275, with the best being 313, and that was deep into the low fuel light (14.2 gallons used, still had 1.7 gallons left). I don't think this is too bad, it is really good compared to what some of you'all are getting. The 8's mpg is about the same as my 01 Mustang GT, and the car has a full exhaust, 3.90 gears, lightweight flywheel, and a full road race suspension. I daily drive it the same way the 8 gets driven. The numbers are almost exactly the same, the Mustang is pretty consistent with 20 mpg and 315 miles to its tank. The city driving and idling do not seem to affect the cylinder engine as much as the rotary.

Sorry for the novel, but I figured there was a couple of people here that were intrigued to see what their 8 could do, I figured I'd share my experience. Do not preach to the choir about "shouldn't have gotten an 8 if you were worried about gas milage", cause I am not. I like using gas, I race cars.

As an Online Race Shop owner looking for products to sell for this car in addition to performance parts, I think some 8 owners might be interested in seeing if they could get better mileage from some mods, such as intakes and exhausts. I have created a webpage on my site for our project with the 8, if you have any advice on what mods I should try and have any experience with certain mods adding mpg please contact me through the site and let me know. I am new to the RX-8 community and any advice or info would be appreciated.

Here is the site page for the project, it has just started so there is not much info there right now. I will add more as time goes by:
http://5xracing.com/p-1057-mazdarx8projectmpg.html

 

welcome, and good luck.

beers