I tow with an '05 GMC Seirra, 5.3, 3.23 posi final, fully loader luxo cruiser. I've added 20" wheels, Corsa stainless exhaust, K&N ram charger intake, Granetilli mass air sensor, and Hypertech reprogram on the computer. Actually, almost as much as the race car. I tow an 1800# Honda on a 16' tandem axle trailer complete with tire rack and storage boxes. Pickup is also quite full. Did I tell you I almost always take way more than I need?

In stock trim, I got 13 mpg, now I get 17...unloaded, 21. That's at 70 with the cruise and AC. Last truck was a '92 Chevy 5.7 w/5-speed manual, virtually the same add ons, and a 3.08 posi. At the same speed, it got 20mpg towing. Difference was in the tranny. No downshift on the hills for the cruise.

I've heard tails of the 4.8 towing similar loads and getting better mileage.