I just purchased a 2004 RX-8 automatic, and well, I'm a bit disappointed in the gas mileage. I formerly drove a 3rd Gen Camaro 305/TBI, and I thought that was a gas hog... well the (fun) little 1.3L rotary seems to suck as much, if not more gas as my Camaro even on cruise control. I drive an 80Mi commute to work, nearly all freeway, and I can't seem to come up with any ideas on how to well, stretch a tank any farther. I've tried cruise, AC/No AC, shifting to neutral when decelerating, and even *ack* driving the speed limit. Nothing seems to impact it at all.

Has anyone here any ideas?

Thanks in Advance.

 

Buy a hybrid. Seriously, the best I ever got was 21 mpg and that was going 70 and 'drafting' behind our trailer. I would consider buying a beater car (Civic or something) or better yet, a motorcycle, if you want to save on gas. It'll pay for itself before you know it.

Make sure your tires aren't underinflated.

 

i heard people get better mpg with 89 ( or 87 with no knocking problem), but still relatively poor mileage should be expected to pay for the fun!

 

The tires are all at 42lbs (OCD helps keep things right)

 

It sucks up gas, and oil... making this an expensive little car. There are other, faster sports cars out there that use up less gas but then you loose the handling and the unique look of an 8. All in all theres not too much you can do besides getting a beater to drive around in but thats no fun.

 

Putting it into neutral when you decelerate won't save fuel.

You will still use fuel to keep the car at idle.

All modern cars cutoff fuel when decelerating. Keep it in gear.

 

so i have a manual. i don't know if this will work out for an auto, but these are my techniques and they have netted me from 23.2 ish to almost 27 mpg (around 26.5). and this is from reading off the odo from the last fill up and dividing by the amount of gas put according to the pump.

1. use premix. i use idemitsu rotary premix. you can get a case for like 50 bucks. it's worth it--protects your engine better and nets you 1 or 2 mpg.
2. draft. not behind tractor trailers, they throw up rocks.
3. at 3500 rpms all of the intake ports open. above this rpm you're using a bit more gas. now, i don't know at what rpm range the AT has because i don't know it's gearing ratios off the top of my head, but on the 6MT, 60 mph is almost exactly 3k rpm. 68 is about 3,450 rpm.
4. i cruise at 67 mph (or for a 6MT 3,400 rpm).
5. shift at 3k rpm. (again i'm unsure of the gearing of AT, but i'm assuming it's similar).
6. accelerate gently.
7. and i just remembered, i use nothing less than 89 octane, but octane ratings shouldn't affect gas mileage. but just in case it's up there.

now using all of this on the highway and wor (wide open roads) when i'm not goofing around or having fun, i net an average of 25 mpg (depending on the wind direction and speed, i bet, and how much safe drafting i can accomplish). i'm going nearly 70 and i'm only losing 4 or 5 minutes to the hour. on an 80 mile trip you'll just have to leave for work like 7 minutes earlier.

hope it helps.

 

Well, 2850 RPM in the AT is approximately 70 MPH, So perhaps the problem is I'm just going to slow . The AT likes to shift well, at seemly random intervals between 2 and 4k RPM, so I'll give it a shot going home this evening driving it in slap-shift mode.

By the way, where do you buy the premix, ( I've never seen it in a gas station or napa, but perhaps it's due to California's goofy smog laws, or I'm just not looking hard enough.)

 

I get my Idemitsu from http://mazdatrix.com/.

You may want to look into an ECU tuning device such as the AccessPORT which will lean out your AF so you achieve much better fuel mileage at cruising.

 

The 2004 AT only has 4 ports so there's probably no RPM point in opening and closing ports But I'd guess keeping it at around 2500 rpm in general will get you the best mileage.

 

i buy it at the rx7 store at www.rx7.com. they have a se3p section which has a maintenance section. you should be able to buy the case or even individual quarts there.

they even have good 10w30 oil, which i recommend you switch to instead of using any synthetic 5w20 engine oil. especially in the summer, the 10w30 will definitely offer much more protection in the rotary than mazda says.

 

No AccessPORT for me, only works with the 6MT

 

oh that's true...

i forgot the at only has 4 ports instead of the mt's 6. does anyone know if the AT leans out ports at lower rpm's?

 

The only time I got better than 24 mpg in my RX-8 is when I pushed it down a hill...with the engine off.

 

My mileage has been into the low 20s when doing all freeway driving, think I went about 340 miles on a tank while driving to sedona and still had 1/8 tank left

 

is moving closer not an option? is 80 miles round trip or one way?

 

There are maps available for the 4AT as well..

 

One way

Well, I work in the valley (San Joaquin) but, I really do prefer living in the bay, makes life much, much more pleasant than living in some well, dead-end agrarian community (grew up in one, can't stand it).

 

www.mazdamaniac.com

 

When you did your research before buying the RX8, what sort of MPG were you expecting to get?

 

To be honest, it was an impulse buy I was sold on it before I drove the thing. I did expect better mileage than a 5 Liter V8 though... and well I finally achieved that today, more to come next post.

 

Well, thanks to the advice of endowdly and neXib I came up with a workable strategy for improving my mileage ( and maybe someone else's )

Firstly, the cruise control is of the devil, apparently, and I would really advise against it. Secondly, driving in slap-shift mode seems to work really well on the both surface streets and on the highway ( I noticed the automatic settings trying to put me in whatever gear would seem "sportiest" at the moment ). On the surface streets, I was shifting at exactly 2000 RPM, so that puts you in fourth really quick, but doesn't lag the engine. On the highway, I kept my acceleration and deceleration as slow as possible, trying to adjust no more than 1 MPH, per second. Drafting a minivan really did help also.

If I hadn't stopped for a smoke I think I would have doubled my highway mileage, running between 2850 and 3250 RPM (65 to 75), but as it stands I figure on an 80% increase in economy .

Thank you all, and I'll post actual mileage figures in a day or two as I fine tune my style.

//Now a _very_ happy RX-8 owner

 

i get 25mpg on the highway with the accessport with the fuel economy flash.

 

Yes your only hope is the Access Port.

 

I've seen 8mpg and I've seen 24.3mpg depends on the driving...i don't think about it anymore jus fill up when I am down tio about a 1/4 tank left