I'm planning to have my car professionaly tuned in the next month or so... but would like to stay all stock. Most professional tuners are claiming a gain between 70-80 WHP on stock Xs after the work is done. Curious... for those who have done this, how much average MPG is also gained? Please post city/highway numbers. Thanks!

 

For increased MPG, the best approach is to adjust driving habits.

As for a tune, my highway driving increased approximately +2 MPG. All things considered, stay out of the boost for mileage.

On the other hand, mileage was not really a concern I bought bought / tuned the car.

 

I usually dont get on my X as much as i used to get on my VIII and i have noticed pretty good mileage for a turbo charged car. I stay out of boost for a good part of my daily drive.....but on the off weekends and let her loose.

 

+1 i had same result.

 

There's a very slight increase in mpg but it won't ever make your forget how poor the gas mileage is with these cars. I'm not complaining as I expected it but the latest flash doesn't work miracles if that's what you are expecting.

 

I noticed no change in "normal" MPG after my tune. How I did notice a little change is if I have a little burst of WOT fun during my commute, it doesn't seem to tank my MPG quite as much as it used to. And if anything your MPG will go down for a while since you'll probably be wanting to enjoy your new tune. =)
Driving habits made a big change though. I went from getting 16-18 to 20-22 (~66%city/33%hw) by making sure to take it easy from stops and not getting into boost, and just overall taking it easier.

 

Yeah, I'm currently averaging 20-22 MPG myself, mixed city & highway driving (yes, I do try to stay away from boost state) currently 850 miles on the odometer. Plan to have her tuned at 2K miles. I read on other tuning threads that a couple of owners were claiming at least 2 MPG on city and 4 MPG on the highway increase after a tune. This is with "normal" driving. I just wanted to verify this with a little survey. This is going to be my excuse to the wife for having a tune job done :-)

 

tuning...it'll register on the ECU and therefore void warranty if the dealer's picky right? bare with me, i'm a newb, but cobb's AP claims it can remap/tune the evo without leaving a trace...therefore, as soon as you "unmate" it, it returns to stock tune. is this correct?

so there's ECUTek and Cobb's AP. are there other methods of tuning?

 

ECUFlash & Tactrix OpenPort Cable 2.0 (plus a laptop)

 

I just have an Ecutek tune and noticed no change in mpg. It sucked before and it will still suck after the tune.

 

I have seen a gain of 4 MPG on the highway in an evo with a Cobb accessport installed on a Cobb stage 1 map.

 

I had no change in MPG (up or down) after tune. I'm still able to average about 20-22 from mixed driving and instantaneous highway mpg of 25+ while cruising.

 

If the tune is good you will gain a couple MPG's. Like others have said however, it really comes down to your driving habits.

 

The light cruise portion of the fueling and timing maps of my tune are stock or near stock, I get the same highway economy. You may get some benefit from leaner settings, but i have not been able to do better than Mitsubishi's latest reflash. The tailpipes stay cleaner tuned, though.

 

That's not bad MPG numbers. I guess my X is really running rich in fuel at the higher RPMs since my city mileage is about the same as my 90% highway mileage (21-22 MPG). Maybe I should try a factory reflash first. Kinda shows it, has quite a bit of black residue on the exhaust tips.