[Otsa580]

My 2010 Silverado ext cab 5.3 4x4 with 3.42's averaged 18 mpg at 75 mph on a 600 mile trip. In town which is 60/40 highway driving I average 15. I do not drive with a light foot because of hills and traffic. The truck has 5000 miles so she is hardly broken in.

I seem to get over 20 mpg at 60-65 but have yet to take the highway on a long trip.