Did I just get under 13 MPG on my 1st tank of gas
 

Well,

1st tank of gas is under my belt. I drove about 178 miles and filled the tank: 13.92 gallons.

My driving was 75% suburban about town; balance was hwy and a bit of Manhattan. Never went higher than 4.5 to 5K and didn't push “too” hard when accelerating. The car is a joy and has respectable low end IMHO. I am not one to do jack rabbit starts but do like to get off the mark quickly nonetheless.

Here is one area I hope to see improve over time.

As the engine breaks in I expect to see better numbers, however I wonder if the engine will give me better mileage if I rev the gears higher before shifting up or continue to shift around the 5 to 6K mark?

Any thoughts? My VIN# ends in 19173 and I thought for sure I would start off with better numbers.

In all other ways, I am super impressed with this car.

Claude H.

Obvious question is how full was the tank when you got it?

Did you fill it or the dealer? I'd wait for a couple tankfulls you have done. And record your perceived driving style for each tank.

In just normal driving, I've found high-rpm use, that is staying in a lower gear than necessary, to suck most gas. E.G., its lots of fun to drive around 50-60mph in 3rd or 4th, but you'll really suck gas then.

IOW, shift up always, unless you have a definite reason not to. 5th works great around town, even 6th is amazingly flexible at somewhat higher average speeds

I am at 12.5 mpg and I have 500 miles on my car......i am hoping for improvement....if not Mazda will hear about it. I drive mostly around town in a suburban area and drive about average......not super fast, not slow. I have an automatic. I'd be interested to here if your's improves.

My first few tanks really got poor mileage. I attributed it to 2 things:

1. unbroken in engine tightness & other mechanical mysteries
2. my unfamiliar nature with the car and the optimal shift points

It should get better. When I refill my tank, it takes just less than 12 gallons, and I usually have 230 miles on the clock.

With all the focus on the forum over gas mileage, I paid very close attention to my results the first 5 or so tanks.

The results were

Highway = 20 mpg
City = 16 mpg

I quit looking at it after that. I think it is a non-issue. If you want 30 mpg by a civic.

I think that's a bit harsh -- most people aren't expecting "30mpg". They simply want the hard numbers to come close to what was advertised. Can't blame them for that.

I'd say my fuel consumption is quite high, I find myself in third quite often round town - it's more fun :)

I don't use the car as a long distance commuter - I wouldn't have got it for that purpose. I got it to enjoy.

My first two tanks have been 16.5 and 16.25. This is about the same as what my truck got so I'm pretty indifferent. If it increases over time that would be cool, but if not... eh, whatever.

-JiM

i enjoy driving the car too much to even think twice about how much i spend on gas. right now i dont give a $hoot, but if u guys are curious im probably filling it up every 3 days. for right now it's well worth it and i love this car. i have no regrets and no problems, and if i can go back in time ill buy this car again and again and again. booya

Short trips eat up gas in the 8, if I just go back and forth to work 8.5 miles, I use a lot, when I go on longer trips like say 50 miles, hwy only I get more economical mileage. And yes I notice if you shift more, (in the manual it says you can cruise at 42 or so in 6th) not as much torque, but that's what downshifts are for. I also use 3rd and 4th going hwy speeds because that's fun, but when I do I get 17mpg or under 50/50 driving.

My mpg just took nose dive recently since the change in temp :(

getting about 15 mpg instead of 22-23 before

claude, why did you round down from 13.92? It's a heck of a lot closer to 14 than 13. Anyways, even within the same model individual cars behave differently. Some will take a while to settle down, so give it some time.

Pyrospawn's observation is very important for the rest of us. He is a single individual who has observed both ends of the spectrum in ONE car. Furthermore, his car was getting pretty high mileage, indicating the engine in his car is not a lemon.

Others have hypothesized that low temperatures may have a negative effect on mileage but those, to the best of my recollection, were across different people with different cars.

Do piston engines see a cold weather dropoff in mileage? If they do, is it as drastic?

Can a rotary owner do anything to counter the effect (e.g., longer warmups)?

Claude, if you remember me, I too got my car from Country Mazda in Huntington. Glad to hear you're enjoying your car.

I am getting between 18-19MPG on my car, and I travel the LIE everyday. I just passed 3000 miles.

Hey RX8Lover,

I knew you were lurking around here somewhere. I love this car. It really is a peice of work and seems well thought out in so many ways.

And to all you others on this thread, hello and thanks for your input.

RX8Lover, you get only 18/19 with mostly hwy driving? How about around town?

Don't get me wrong guys, I never expected to get mid 20's MPG here, however I would like to get 20+/_ driving about town in a normal, if somewhat spirited, manner.

As I am just breaking in the engine, I am not pushing it and haven't even passed 5K revs yet. Although my right foot is beginning to twitch a bit to see how it feels hititng 7 or 8K+.

How long do I wait tilll I can run it up a bit and be safe with the engine? 600 miles or more?

So my millage is absed on driving mostly around the 2.5 to 3.5k rev area.

Thanks again guys.

Claude H.

Life on the LIE isn't exactly highway driving, as more often than not it is a parking lot. But I do take the HOV lane, where I usually cruise at 70 in 6th gear. However, I won't lie and say that I never go to 9000 rpms...I do, many times. The engine revs so easy all the way to redline that I can't help but do it, plus it's fun. I didn't start getting on the engine until 1000 miles.

I think this engine runs richer than it has to, but thats just my opinion.

Boy some of you are tough.....Buy a Civic....not necessary to state that! We just want something close to the stated mpg. 12.5/13 mpg city to me stinks and I would be happier if it was at least around 16/17 range which is below the stated mpg. I love the car but I hate having to constantly worry and look at the gas gauge! I am not expecting too much just reasonable gas mileage.

On both RX8's, I have consistently gotten in the 18-19 MPG range. I think the lowest I ever measured was about 17. First car had about 4K on it when I returned it, new one has almost 2K miles. Mostly, I commute in the SF Bay Area (highway 880 for those who care). The milage is slightly better than my 91 RX-7 convertible, and slightly worse than my 82 RX-7 (from what I remember). It is definitely better than the 12MPG I get in the Durango. When they do the measurements to determine highway milage, I suspect it is running at a constant speed of 65-70 MPH for long periods. What I see is that my morning commute is anything but constant speed, driving anywhere from stop-go on the freeway to significantly over the speed limit (but going with the flow) for short periods of up to a mile or two at a time. Coming home, I have hit significant speeds (I come home late with little or no traffic), so I am quite happy that I am getting 18-19. Even the one tank I had that I was able to cruise for a large part of it at 90+ got me 18.

Of course, if the fuel milage was really a problem for me, I would drive my wife's Prius :).

Oil viscocity affects gas milage in piston cars, not sure on rotaries, I'd expect the same though. Thicker oils tend to produce lower gas milages, possibly because the pistons have to fight the thicker viscocity harder in order to produce the same amount of output as a lower viscocity oil. Lower viscocity oils have also been known to produce a few extra horses on the same car. IE: 20w50 VS 0w30, the 0w30 tends to put out an extra 2-3 horses on a chassis dyno.

In the winter, the oil isn't as...fluid-like due to the coldness, so with that said, I suppose it is possible for it to affect engine performance, which in turns, effects gas milage.

I guess I am lucky,normal and just right. I average 18.4 - 18.9 in very mixed driving even short trips around campus 2 miles around. I check every tank. More fun = less mileage but in tenth's not gal. If your mileage is in the range of 12 mpg you have a problem. I would plan a trip fill up get on the freeway where you can go unheeded set the cruise on 60 and go 150 - 200 miles. Stop fill up and check the mileage it should be over 20 mpg. If it is at 16 - 17 mpg you have a gas hog. I would have the ECU checked at the Dealer. Mine would be replace one way or the other. This car loves gas but it's not a hog. Also check your tire pressure. The higher it is the better mileage you will get.

i dont know about the rx8's...but i do know that most people start reaching their optimum gas milage when they are a couple thousand miles into their engine and its fully broken in. I know it took about a thousand miles on each of my motorcycles to reach optimum milage.

Ways to improve mileage
 

The Rx-8 has relatively large and heavy rolling stock. i.e. a lot of inertia and rotating weight in the wheel and brakes. I would venture a guess that smaller wheels or forged aluminum lightweights would do something for both gas usage and Wheel horsepower. Have you ever seen what happens on the dyno when a car get's "upgraded' to bigger(heavier) wheels? The power drops in measurable amounts and that mean the loss of mileage and power. I love the look of big wheels too, but that is the price you pay. That's one reason why honda and toyota have been so conservative on wheel sizes until lately, and many of the larger wheels are of a lightweight design. I am planning on some forged aluminum wheels in the 13-15Lb range, and I expect to see a gain in acceleration as well as mileage. The 93' RX-7 had lightweight 16" wheels and it pulled 1.00G on the skidpad. I see no real need for large heavy wheels, and they do far more harm than good. I wish I could go to 16" wheels, but the brakes probably won't fit, and the wheel wells are too big. They would swallow the 16" wheels up!

Ya...the brakes are freaking massive, I think that even dropping 17's into there would be extremely tight to find a set that would clear the rotors properly.

I am on my fourth tank of gas. On the third tank I filled it with regular as compared to premium. I did this as an experiment to see if my RX got better mileage on regular gas as opposed to premium (this has been discussed on another thread). I drove 203.1 miles and with one tick mark below 1/4 full, I filled it with 12.303 gallons of gas giving me 16.508 miles to the gallon on strictly stop and go urban loop driving with only one 10 mile loop of interstate driving. On my first and second tank I did get noticably worst gas mileage (13.2) with the premium as I was only able to get 170 miles or so out of it before needing to fill up. I so far am happy with the gas mileage I am getting. I do not flog it as some might do but I drive it they way I want to enjoy it.