I would never own a gas rig again for towing. Mine gets 15-17 around town and highway, 8.5-11 towing a 40' aluminum goose neck, chipped, exhaust, intake, stock tires and wheels. I tow around 75-80mpg but have tried to haul slower, doesn't much matter. It's a 2004.5, 3500 dually, and I laugh at people who quote 20+MPG, it's BS in my opinion. Every time I get in somebody's rig that gets that kinda mileage, it doesn't. Great power though and long living if you take care of them....