The first road trip with my '05 Sierra was from MA to Bowling Green KY to pick up a Covette. I then continued to Panama City Beach before heading back to MA. Most of my mileage ranged between the low 9s and low 10s. This was pulling a 24' enclosed car hauler that weighs about 10,000lbs loaded. I was running about 70-80 most of the time (tried to hold about 70). I recently sold that trailer and will be pulling a 32" aluminum enclosed with a V nose. Hopefully this will help with mileage during this year's track trips. I'm also getting close to the magical 10,000 mile number. Alot of people say they mileage improves after that.