MPG's and spare tires
 

I'm getting the lower side of MPG's on my 06 RX-8. (6 sp manual and only have 25,000 miles on her.) about 16 mpg, city and hwy. Not happy with it. A mechanic friend of mine that works on rotaries said I should get better than what I do.

I've only had my RX-8 for two months and love it othewise! I got it from Carmax and have an extended warranty that I don't want to void it!!

I would love any and all serious suggestions for improving MPG's, from cheap to more expensive w/o screwing up my ext. warranted.

Also, any suggestions on where and/or what kind of cheap spare tire I could pick up and throw in my trunk? Don't like fix a flat kits.

Thanks Y'all! (A happy RX-8 driver in Chambers, Co. TX)

GFC34.

16 mpg mixed sounds about right.
get a complete spare tire kit go to for sale section.

Mine went from 16 to 21 mpg highway when I plugged vacuum leaks at the hose fittings on top of the intake bellows. Might be worth checking.

It depends on the mix...not really enough info here.

50/50 city/highway?

Are you driving it hard/revving high?

What year is it? Have you had a routine check up recently?

Are you running aftermarket wheels and tires?

City driving can absolutely kill ur mileage. Short trips especially. When I had a 2 mile commute to work I'd avg 13-15 mpgs. Highways keep it under 70 in 6th and you should see low 20's easily.

So 16 might be just right. Pay attn to where you're shifting in city driving.

Other than that...typical "check plugs, coils, etc".

Regular scheduled maintenance, set recommended tire pressure, don't floor the gas pedal too much, and don't keep heavy stuffs inside your car, unless you have too.

These cars can have wildly different MPG. One guy was getting mileage like yours with two engines, on the 3rd one(first two failed) his mileage jumped up to 21. Another guy had one RX and was getting good mileage bought another and his mileage dropped by 4MPG, driving exactly the same roads. Mazda's quality control for these engines appears to be questionable at best.

I have tried every thing to increase my MPG on this car. I have tried all the following:

Higher tire pressure.
New coils and plugs.
New airfilter.
Premix.
High octane/low octane fuels.
To the dealer half a dozen times (worthless people with no interest to help)
Different oils
Different tires

Nothing made a difference except one thing. I bought a scanalyzer II which gave me a read out of real time fuel consumption. I found by monitoring this it adjusted mt driving habit to the point that I was saving about 1.5 MPG on average. In the end I got rid of it because I was spending more time watching the MPG then enjoying the car.

So, short of getting a new engine you are stuck and even a new engine is a crap shoot as to getting a good one or not.

if you want to get better milage dont buy a spare tire, as hauling around the extra weight all the time is not gunna help your milage. also my best mpg is 19.5 and that was 3 days of drafting trucks on the way to work and cruse at 70 on the way home. my commute is ~25mi of which maybe 1mi isnt highway.

You should of known that these cars are not known for mpg's. Like one said, enjoy your car rather than worrying about your gas milage. I average 16.6 mpg's on a new R3, fyi.

There are mods you can do that should help it a little. Best thing would probably be the BHR ignition. Seems people get much better mileage with those.

'06, 17~18 city, 21~23 highway.

Lowering your car helps also in terms of less drag and I found I got more consistent higher mpg results on the highway.

True, and yet I actually carry a heavy full-size tire as a spare and still get 21ish mpg in typical commuting driving, failing coils and all ;)

Has anyone documented this? I would be interested in actual data.

I remember a couple of posts saying they jumped up a good bit. Like 18 combined to over 20 combined. It was in the BHR ignition thread I think.


Carrying a spare tire won't make as much of a difference as you'd think. Weight doesn't have that much of an effect on mileage. Not saying it doesn't, but not that much. Weight on the wheels has more of an effect than weight carried by the car.