2001 Silverado with 4.8L V-8, automatic, 2WD, no performance mods - it's all completely stock.

I do almost nothing but city driving and get 13.5 mpg. If i take a road trip, say Dallas to Houston, I'll get 16.5 mpg if it's all highway.

Consider, I do have the added weight of a bed liner, loaded tool box and over-sized all-terrain tires.