17,500 SERIOUS mileage change
 

:rock: Never ever a single problem for first 17,500 miles. Always get 14-15mpg city and 18-19mpg highway, just the way it is. First time refueled after 17500 and mileage was 18.3 city, second time 19.1, yesterday 18.4, all in CITY! This is a great WTF. I read a few threads in the past where others had this happen, but other than a great car, I never thought anything that happened in HERE would happen to me, but, this is REALLY happening. For control, nothing else has changed, same fuel station, same fuel brand, same fuel octane (87), same finger on the calculator, even the same drive. Perhaps its black magic, but I'm taking it!

dang, i read the thread title & thought you were going to say something about how your odometer jumped from like 17500 to 80000 overnight... guess i was pleasantly surprised. congrats on the blessing! somebody likes you...

or it could be the engine is fully broken in

or the new ethanol mixture gasoline

or maybe black magic, lol

You are not the only one. My highway mph average last time I drove to Duluth, a 340 miles trip I average 25.5 going out and 26.3 mpg coming back. This was done with set cruise control at 72-74 mph the whole way. My mileage has been this way after 12K miles has gone by. I am not complain about my mileage.

Ronn

it would appear that i enjoy my 8 twice as much as you.

WOAH - that's the best I have seen. I'm at 21 combined.

I've seen that too. I used to have to really baby it to get 22mpg on a highway trip w/ 87 octane. Now I seem to easily get 25-26 on a straight highway trip and 21 w/ 50/50 highway and city. I wonder if also the 8 likes the ethanol?

I should mention I'm at 21500 miles.

maybe we are all driving it nicer subconciously after 3.00 gas...

^very good point lol

i'll keep my eye on this tank i'm running right now; it is the first full tank since i did the new plugs/new starter/new battery upgrade, we'll see if that helps.

before the upgrade i've averaged a solid 19.5mpg over the lifetime of the car (32600 miles)

I am convinced from week to week that gas stations get different blends. Most of the time I get 15 in the city and 19 highway. One time after filling up with 87 at one of my regular stations I somehow managed to squeeze 75 miles out of less than a quarter tank of fuel.

I don't know how it happend, but I notice my mileage has been suckin a bit lately. I'm gonna get my oil changed today and start the process to converting to (dare i say) full synthetic.

the oxygenated gas is gone now. so your mpg has gone up. didnt have the car last summer, did you?

I'm sure if I'd get 19-20 mpg if I didn't redline multiple times every day.

That is amazing, I wish it would happen to me. Mazda really has a can of worms on their hands with the Rotary. Some get great mileage and other suck and there is no rhyme or reason, which you get. I wish Mazda would get their act together.

I purchased the car in Dec 04 (it's an 05). I don't drive to get mileage but I also don't drive to get reckless driving tickets, it's a sports car and thats how I drive. I realize these "mileage" threads can go forever. I practice statistics for a living and four more data points (fill ups) officially makes the perception a statistical reality (black magic excluded).

QFT

I can get the same effect by driving over to Wisconsin (no ethonal at some stations) vs. filling up in MN.

Milage goes from a constant 18.6 to 23+

Miles...
 

Gone over 30,000 miles, no change here.

S

This is odd because the fuel contains only 10% ethanol at most and ethanol has about 60to70% the energy as regular gas. You should only see a 3% to 4% reduction in mileage. If your getting 20mpg you would go down to around 19.2mpg.

Ethonal is also a drying agent. Gas that has ethonal in it can have more water as well. In my experience, gas blended with 10% ethonal is poorer quality gas all around than that stuff that doesn't use it.

They have. They actually built the RX-8. Any other manufacturer even try anything that radical in this price point?

Go drive a Camry. I'll keep my '8 and all of its quirks - including wildly fluctuating mileage.

gas mileage does go up in the summer, my saturn has experienced a boost in mileage as well.... add warmer outside temps with a summertime fuel blend and mileage for me has jumped 3-4 mpg.

Subaru WRX, 350z, ect... All nice innovative cars.

RX-8 is a great car and has some real plus and some real negatives. Don't let the fact that they built the car blind you from the fact that they didn't implement it correctly. The car has been detuned hp wise and the gas mileage varies all over the place from car to car. The worst is that Mazda has done nothing to fix it. You can be a sheep and just keep saying "but it’s a great car so I'll live with it". As for me, I want to see them make this car into the best it can be.

Simple fact is if they don't resolve some of this issues your beloved 8 will be come part of automotive history.

ive noticed on my 8 that regardless if i go 70 or 80 i still get 22 mpg hwy, no city driving, prob a lil here n there, but im happy with it.

If you like boxes and truck chassis. Those are evolutionary developments on existing platforms guided by bean-counting, not engineering vanity projects that exist solely for the purpose of their own satisfaction.

Don't let the fact that they didn't market it correctly blind you from seeing that it wasn't designed for you.

It wasn't "de-tuned". It got trapped in its own marketing hype. Uniform gas mileage is the result of "de-tuning" a car to the point that it is in uniform control. As soon as you start tuning a car, that gas mileage goes right out the window, regardless of marque.

Nothing to fix. Mazda corporate has just been back-pedaling as fast as they can. The failure of the RX-8 will be uniquely one of death by mismanagement.

You want them to dumb it down so that it conforms to American box-sedan mentality.

If they don't "resolve some of this [sic] issues" all they will do is loose you as a customer, which would probably be just as well since you don't get it.

Wow, you’re really in your own little world aren't you? The car was detuned to extended the life of the Cat as mandated by the new US government regulations. Rather then beef up the Cat they richened the fuel mixture. End result decreased mileage, decreased power.

When the WRX came out it was rather unique and a gamble that paid off. There was nothing at that price point that could touch. Don't fool yourself into thinking there are no other unique or special cars on the road. God did not make the RX-8 just for you.

Have you bothered to look at sales figures for the RX-8 over the years? The cars sales have been sliding steadily. Why is this? Poor fuel mileage in a time of high gas prices. Poor response to known problems. A rap for being a slow car compared to its reviles. These are simple facts that sticking your head in the sand will not resolve. Mazda can resolve these but has chosen not to.

I really like this car, it is plenty fast for me, good looks, nice build quality but 11mpg is a killer and I would like to see Mazda fix it. Don't be so damn blind to the warts on this car. You can still like the car while looking to make it better. That is how the car will survive. Your blind faith approach may make you feel better when the light go down but it those of us who question the car that will help it survive.