Got 12mpg with my 7000lb truck with 4 alternators and 26" rims towing a 4500lb Hhr.
On the way back it was more down hill I was getting like 15-16mpg.
When I got to the car show the first demo I was giving my fan that cools my radiator fell off and almost took out my radiator 300 miles away from home... My buddy Jeff put a new water pump and fan on right at the car show in 30mins. He is a life saver and awesome guy. Other then that my Tahoe ran awesome.