I read somewhere that unlike other cars, the mileage for an RX-8 is the same whether driving at 55mph or 85 mph. Is this true? There are so many myths out there that it makes me think this one is. After all, I have met folks with over 80K on their original engine who have never used pre-mix or the fancy oil and filter brands recommended on this list, never "redline each day" or ever redlined there cars and are happy as hell. They like the handling and they like the looks and can afford the low mileage around 16 that they get.

 

Myth, unless the car is tuned very poorly. Red line a day, also probably a myth if you sort the the blown engine threads, esp since it's often done with a cold engine. 16 mpg? I've averaged 21 over ~20k miles.

 

red line a day is fact

5w20 is garbage is also fact

they don't feel there is a problem cuz either they are retarded, or its just degrading slowly. I didn't know my engine failed compression if I never ask for it. does that mean it works? sure. ideal? far from it

people who has cancer usually feel fine and seems happy until one day they just fall down. hope that example gives ya a better idea

 

How do you average 20+? I can only do that when I am drafting behind a truck or SUV. At a steady 70mph, highway only, I get 20-21 and in pure city driving each day 2-3 miles one way, I get 13+ and in combination, 50/50 about 16+. I have a 2009 GT.

 

The threads are full of folks who redlined a day, and are now in their 3rd engine, people who decided their RX8 need to be driven at high RPM with pre-mix and expensive oils and more and then the old librarian where I work is at 81K (lots of folks redlined and lost their engines), still delighted with her RX8.

I would rather feel fine and one day, when I am 90 just fall down than to be told I have cancer, get radiation and chemo, go broke paying medical bills and still die young. All the folks do is get to spend a lot of money for no reason.

 

Sometimes you get bum engines. I had 3 of them. I know how to treat a rotary. The RX8 wasn't my first rodeo cowboy. My present engine has lasted longer than the first three combined.
It's not necessarily how you treat the car when they are defective to begin with.

 

I get pretty much the exact same mpg that you do. The variety in different owner's mpg (with equally properly functioning 8's) is entirely driving habits and conditions.

 

That's a myth. Any car uses more fuel when you drive faster.

 

FWIW, my original 2004 engine averaged around 18.x mpg from day one for it's 80,000ish miles. I managed 21 on a few highway trips.

My replacement engine has averaged almost 21 mpg over 10,000 miles. Same commute, same driving style. It gets 24 on highway trips.

So I'm guessing it's not ALL driving style, different engines act differently too.

 

My daily commute is 75 mph round trip, 90% hwy. I cruise at 65 mph and I get 22-23. It is attainable, just use cruise control more

 

My AFR's are actually richer with cruise control than with a steady foot.

 

nah...correct me if I'm wrong but the most common reason for engine failure is low compression not abnormal bearing wear (which is what 5w20 would be responsible for)

I think what people mean with statements like that is that the RX-8 has poor fuel across the board regardless.

So you might as well drive the car hard since driving like a granny doesn't seem to save much gas anyway.

 

I still love this car...no matter what the myths are.

 

the mileage really doesn't seem to vary much between 55 and 70 (i've never tried faster). i've had a ton of different Rx7's, and those exhibit the same behavior, i think you can attribute this to the good aero, the low friction of the engine, and then the engine is geared to be in its efficiency range right in the 55-70 area.

the interesting one was my 79 Rx7, we drove it to sevenstock twice, which is a 1000 mile round trip, and that car gets it best mileage between 3500-4000rpms, in 4th this is 60-65mphish, and in 5th its about 75-80mph. if you run it over 4000, mileage drops quite a bit. under 3500 mileage also drops, not by a lot, but it does. the sevenstock trips it was doing 23-24mpg.

i agree, it seems like the people with the most engine trouble are on this forum. my friend bought one of the first Rx8's, and its been nearly trouble free this whole time. its got something like 85k on it, factory engine, coils, etc etc. its due for some work, but what other car can you drive 90,000 miles without even doing the services?

i don't think you need to redline the engine each day, but i do think its a good idea to run it high enough so that all the valves in the intake operate. 5w-20 oil is fine for a street car. its too thin on the racetrack, but that's not where we are.

the handling is the best part of the car, its an amazing chassis. its so natural, has no vices, and it rides well too.

i just bought one, and i'm still pinching myself, its an amazing car.

 

because **** happens,

and it's known fact it's very , I mean VERY EASY to mess up a "supposed to be easy" Rotary Engine rebuild.

Sorry but Butt Dyno doesn't work as good as you (her?) think.

and location, quality of gas, driving habits, LUCK, etc. ALL matters.


So are you saying everybody dies anyway, you never have to take care of yourself? Junk food as your main dish and you just sleep and eat everyday?

 

you do know why bearing spec matters, right ?

it does effect engine life, try to run an engine with worn out bearings, and you will know.

the point should be, when people comparing mpg, most of the time they dont even have the car they are comparing to, (or neither of them), all they compare is what he said she said

when they really got the car other than rx8, they still get the 13mpg that they said "rx8" gets, but hey, they just gonna say they are lucky they got that car cuz in Rx8 they will probably get 8 mpg, makes them feel they made the "wise" investment.

 

you're done with 2nd gen dude?

welcome to the dark side ...

 

ha, i wish! i still have two Fc's and a 1st gen....

 

I know for a fact that I get same mileage at 55 vs. 85 mph on average. It's 19-20 every fill up regardless of how I drive.

 

This

230 mile round trip to my mothers. Cruise control on at 60, 21 mpg. On the way back cruise control set to 80 (speed limit 75) 20 mpg. This is based on refilling the tank until it stops and with the help of fuelly. Filled up when I left and filled up before I left on the return trip. So go figure. Every other car I own as speed increases mpg decrease.

 

Please close this useless MPG thread.

We already have over 5500 of them.

 

In general, I agree with you. However I can't use that as justification for closing it.


Mileage is indeed a mythical beast. Some are in full belief of what is possible, others are in full believe of what is impossible, and the only people that are willing to swing from one to the other are usually not doing their research. I will avoid using the term 'gullible'.

 

those 20 mpg is a LIE! cuz according to all these "oh I never even know how rotary engine works Vtec rules y0!" guys said we get less mpg than a Ferrari at full throttle!

 

There is more to the original post than MPG. It's just those recently have posted about that.

If you don't want to read about it, don't look.

 

Getting back to the OP's post - IMO it doesn't matter the speed at which you are driving, what matters in at what RPM you're cruising at. AFR's don't lie, if you think you are getting the same mpg at lets just say 14.7:1 vs 12.7:1 then you are an idiot. As far as the premix and type of oil goes, just look at all the engine rebuilds and what they used. Or look at pettit racings website and see what they claim about their protek unless you feel they are BS for marketing purposes. There is also an entire thread with oil analysis from labs.