Wind resistance is the biggest thing.

Before I lifted my truck, i was getting 26-27 mpg if i drove 55-65 whole time.

Now I can still bust out an 18 every now and then, and that's with big ole tires. Think truck was only rated at 19 new.

Normally i get 12-14 tho. (i normally set cruise at 80, and that's a lot of wind)

Full synthetics, ud, electric fans, intake/exhaust/programmer.