I have seen as high as 23 mpg on highway driving around 70mph. Less if i go faster. A little more if I cruise slower. City driving I don't even bother to calculate !

My 2008 40th Anniversary Edition has a Mazdaspeed CAI, BHR ignition, Racing beat oilcooler/condensor screens, Remedy low temp radiator thermostat, Rotary performance oil cooler lower temp thermostats, and lower temp cooling fans relays. Driving on Conti Extreme Contact DWS-06 tires. Using 93 octane top-tier gas. Premixing. Religious about regular and preventive maintenance.

23+ honestly, roughly 25 if highway. Fuck all if city. When the car was completely stock I was getting 25. I've noticed the car likes to do it's best mileage at high revving, so, I tend to keep it above 6k if I can. Wife doesn't care for it though, says it scares her.

Actually, a few of you may recall my first post, which was when I'd just bought my 8 and took it 1600 miles back to CO from MD. We averaged 25 MPG at 75-80 the entire way.

I am getting 14.747 average after the last 5 fill-ups. Primarily city driving but I take it on the highway here and there. Car is bone stock. Using 91 octane gas, no premixing, 5W-20 oil.

Lowest: 13.299
Highest: 16.819

That seems kinda low mileage ?. I'm pulling 20/21 mpg mostly in city. I also premix and maybe this makes some of the difference ?.

How are you measuring? Unless you are driving on flat roads with the cruise control set at 50MPH, there is no way you are averaging 20/21 in the city.

I'd agree - on my 2010 GT here's the distribution of gas mileage vs. % city driving relative to outdoor temperature. I find it hard to get 20/21 in city unless your % city driving (I dfine as miles spent in the 0-30 MPH range with street lights/stop sign stops).
https://cimg5.ibsrv.net/gimg/www.rx8...dfdbc22c1d.png

WTF? If I even get above 2500 rpm mine sucks gas! Anyone getting above 20 with a stock car needs to contact me and let me know how they do it and to prove it beyond dots on a paper that anyone can create.

Who knows, maybe I bought the car built on a friday at quitting time or something.

Most of the people who claim crazy good mileage is because they are using a scangauge or similar device to measure rather than than actually calculating gallons and mileage at fillups. No one is averaging 25MPG in an RX-8 unless they are cruising down a flat highway with the cruise on below 70MPH.

I agree - all my calculations are easy math - not that new-fangled core curriculum math. Here's my equation using the olde fashioned method:

1. fill up the car tank to the same point everytime
2. record the actual miles on the receipt along with temperature and estimate of % city driving and premix addition
3. actual mpg = miles driven / gallons used
4. record in my e-log book
5. monitor for trends

For example my mileage has been steadily decreasing and prompted me to perform a few maintenance tasks early in cluding - new C revision coils, plugs, and wires. I'll update everyone on the effects of new ignition health once I've gathered a few tanks worth of "real" data

Yeah my 8 gets about 12MPG so I don't track anything anymore, :lol:

here's the data
https://cimg1.ibsrv.net/gimg/www.rx8...2f613612a2.png

14-16, with a lot of interstate driving, possibly exceeding recommended speeds.

I don't have fancy scan tools, so, we did most of our math by guestimation and watching the gauge, and recording our mileage at every stop, while attempting to stop consistently as well. As of now, I know that when I drive a shitton in the city I'll need to fill the tank after 120 miles. If it's all highway @ 75 ish I know I generally average 250-260 a tank. I also know that from driving this car it likes to do better at high revs. I can drive from Denver, CO, to Boulder, CO, to Estes Park, taking all the long and curvy back roads and keeping it in the high revs (above 5k) and it'll just pull all day and I'll come home with probably 60 miles left to spare on the tank, if not more.

edit - I ALWAYS fill the tank when it gets to the last 1/4, or right before it hits that. on the gauge, which is 95% of the time a little over 3.5 gallons left in the tank.

I've noticed when it gets that low you can almost watch the needle drop, seems like it moves faster.

I'm glad I'm not the only one that noticed it... I thought I was seeing things.

"math by estimation" is an oxymoron.

So is organized anarchy, but I remember seeing that on news as a kid.

Whew!!! I was worried I was too much like Band–Aid, Stuck on Stupid.

2010 sport AT, 44k miles, all stock

100% highway = 24-26 mpg
100% city = 15-16 mpg

The attached graph shows nearly 3 years of fill-up data since I purchased my RX-8. The spikes correspond to long highway trips, and the valleys to short trips of less than 10 miles on city streets.

https://cimg7.ibsrv.net/gimg/www.rx8...ef641f72d6.png

The best I can do with my RX8 with a tried engine is 22mpg. This is mainly highway 55-65mph though with a little city driving mixed in. The lowest I have seen it at is 20mpg.

Looks like I am right in the ball park with what I should be getting with it.

HTH

David

That is truly amazing that you are getting a minmum of 20 mpg. Unheard of in the RX8 world.

im getting roughly 350km per tank...jesus XD

I do, never have seen it under 20mpg and I don't always baby it either. Always try to hit the rev beeper at least once per drive lol

When I said tired engine it's more of an assumption that it is. It has a hard time
Starting when hot especially in the summer months. Plus i can hear a slight miss at idle when it's hot too. Already replaced plugs, coils and wires. I'm sure it's compression related, plan to tear it down this winter.

Figured now that i have actually driven my 8 since 2014 i can post up some MPG's. :yelrotflm
Overall i think its pretty solid. It slowly declined up to now, mainly due to extreme temps, being down to 10F often, i would let it warm up some, and also, no more highway driving, Since October, it's strictly been city driving :/. I do open it up quite a bit however! :D

Not that it matters but..
Gas: Shell V-Power
Oil: Rotella T6 (5W40)

Attachment 217425

I use the road trip app to keep up on my fuel and maintenance costs. I've only driven just over 2400 miles since I got her in late 2015, but when I'm mostly highway, I'll get about 23 mpg, and even in worse case scenario such as winter, snow, extreme cold, short trips, I don't have a log under 15.4 mpg. Maybe I'll take a long cruise some day and see if I can get more than the 23, but not too concerned. Every engine is slightly different, some win the lottery and get no lower than 20 mpg, some lose it and get lower lol

A trend I did notice from the app is 93 seems to get me better results than 91; but that could be attributed to the average tank with 93 coincidentally getting more highway miles on average as well, too small of a sample for such a result. Trying to find the right gas stations at the right times; there are 91 and 93 no ethanol, then ones with it. I try to get to one with 93 without ethanol, or just no ethanol in general, but I don't go as extreme as creeping through gas stations reading pumps, and moving on if I don't see a 'clean' 93 :P

I just try to appreciate the beautiful beast for what she is, and have as much fun and enjoyment as I can legally while in her ... that sounds a bit weird but you know what I mean :fruit: