i changed mine at 15, and 25.

 

Changed your what?

 

Fuel filter, I think.

 

Here is the rundown on gas mileage on my car and my wifes car. Both are V-6 auto and Both have true dual exhaust. Mine GT take offs and hers JBA. mine had a drop in K/N filter. We recently ( mid july) went on a road trip with both cars 700 miles one way. She averaged 29.9 and I averaged 27.6. In the city I average 23 and she averages 22.6.

I traded my V6 for a GT manual on 1 aug. This car gets 22 mpg city and 25 highway at 70. if I run 79 I drop to 23. based on a 90 mile one way trip.

 

I average 19-21 mpg in the city (Tampa stop & go traffic). I average 240-255 miles per tank.
No long road trips yet to get the HWY mpg.

 

OK, I've had my GT long enough to see how the mileage compares between the V6 and GT. The mileage on my 05 V6 auto over 30k miles averaged around 24.3. Mileage on my 07 GT manual (with 3.55's and at 1500 miles so far) is around 22.7 on the exact same commute.