I don't exactly get it either. I just sold my 02 I35 that was a bit of an oil burner (1 qt/1000 mi), and I got 27+ mpg with that car. Bought the G thinking, smaller car, same basic engine, should get at least that mileage. But, I'm driving the same roads every day to work, pretty much the same driving style, actually even more conservative4 because the mileage concerns me. 90% highway, 70-75mph, easy speed up, minimal brake use, trying to squeeze out every fraction of an mpg, and get, at best 20.3.

Must be the tuning? I wonder, could you pull an ECU or reset the "programming" for the ECU basued upon the I35 and impact the mileage? Just thinking and dreaming...

 

I don't know if its just me, but it seems some get better mileage than others. My first G was an 06 Sedan 6MT and I used to get 330 miles to the tank city driving when the light came on, and about 450 miles per tank on the highway......I returned the car at the end of the lease.....and I just recently bought an 05 Sedan 6MT but on this car I get about 290 miles to the tank on city driving and about 380 to the tank on the highway...I pretty much have the same driving habits and same drive routes, so what gives? both cars had only a K&N drop in filter and no other mods other than suspension...??

 

holy thread revival batman

 

Lol but seriously I get 15 mpg and it sucks

 

I avereaged about 22 before the twins went in. I get much worse now but havent done a full tank and odometer trip reset to see.

 

When I got my car in 2011 I could just barely get 300 miles on a tank now I'm lucky to get 220. In the next couple weeks I'm switching to full synthetic oil, diff fluid, and doing a drain and fill on the trans. Also replacing the pcv valve and spark plugs hopefully that'll help.

 

I used to get abt 320 per tank on my 05 get coupe. That was abt 2 years ago. Now I've been getting 270 per tank or roughly 18 mpg for the last year. I've changed the engine oil, trans fluid, diff fluid, and plugs but still get the same mpg. Good luck on yours