I tow with an '02 Tahoe 5.3L w/tow pkg, fairly heavy open trailer with box, 1800# ITC Honda. Several hundred pounds of stuff in trailer box and in back of the Tahoe. On flat terrain usually tow 70-75 mph, down to 60 for larger hills. Haven't really been in big hills yet. Usually average 12-15 mpg unless there are a lot of hills. I've been pretty pleased, it rides well and has decent torque. I've been wanting to add a trans temp guage just to keep an eye on things.