jrmy

yea i have the v6 version with 22in. rims and my gas mil is HORRIBLE, the rims r like 5 times heavier than the stock ones HORRIBLE HORRIBLE

ZX1100F1

2007 1500 Reg Cab Short Bed 2WD New Body Style 4.8L / 3.73 gears.

I average 18 mpg

Worst tank has been 16, I have got as good as 23.5 MPG Hwy at 65mph.

At 295 horspower don't let anyone tell you that the 4.8L won't do a great job, not so many years ago the 454 was only 230 hp.

The difference between the 4.8L and 5.3L is the length of the stroke wich accounts for just a 20hp and 33lb/ft difference, while this is noticable it is certainly not epic.
Most people who bad mouth the 4.8 have not owned it and are thinking of it in the same light as the old 5.0L which was a dog in many applications.

BassinProf

Another issue about fuel mileage when you increase tire diameter is that thespeedometer thinks you're going slower than you actually are. There's a formula for calculating this somewhere but it's something like if you go from a 31" tire to a 34" thespeedometer is going to read about 50 mph instead of your true speed of 55 mph. This means that your odometer willshow you travelling less on the same tank of gas, hence lesscaculated fuel economy.But of course this lost fuel economy is not true.