I get 450 to a tank or 23-25 mpg regularly. 80% hwy. A couple tanks ago I TRIED to actually get good gas mileage....I averaged 29.1 mpg that tank.

 

I'm running around 21-22 mpg on a 50/50 mixture of highway and city driving. I have a '05 sedan with 72k miles completely stock. If I put my foot into it everywhere it only drops to 19-20 mpg.

 

I avg around 22-26 mi a gal. Mix of city 30% High 70% 04 6mt sedan

 

I drive the crap out of it and get 22 MPG average. 6MT and 2003 though.

OP, how are you calculating your mileage? You do know the Display is not at all accurate, right?

 

When I put on my Stillen intake, I got crappy mileage until I did the throttle body re-learn procedure (or whatever you want to call setting the idle properly using the procedure). Good luck.

 

i get a mix of 19-22. i do about 50/50 so i wonder what i could get if i did more hwy.

 

I am getting 10-11 L/100 kms, which translates to 21-23 mpg doing very little city driving. A little worse when I fill with Reg. I guess I will be happy enough with those numbers. I think another big factor is that I live in an area of mostly 2-lane blacktop and drive at 100 kph rather than the 120 or 130 that everyone does on the expressway. I do enjoy passing on these roads!

 

I get 21 avg. to and from work 52 miles round trip with a mix of city and highway and have a 04 x with z tube and coupe mid with hks muffler and I drive the car somewhat hard

 

I have lived in both Dallas and multiple locations in CA with the same car.

I can attest first hand that gas mileage and performance are better outside of CA. Our mixture is hard on the Fuel Injection (FI) system, especially the 'winter' mixture. This year mileage is at an all time low, in both of my cars (the other is a Honda Pilot)

For example, in Socal, I was reading that fuel must contain 2% oxygen by weight, resulting in a mixture of 5.6% ethanol in gasoline. The resulting fuel is referred to as reformulated gasoline (RFG) or oxygenated gasoline, or in the case of California, "California reformulated gasoline".

I'm not a chemist, but there is a noticeable difference.

This is one of the reasons why the FI additives such as Techtrol/Lucas are a good idea once or twice a year.