Have a 2006 Chevy Vortec Max,6.0 345 HP Crew cab, 410 gears, HD supension. 14-15 MPG. Had a 2002 5.3 373 gears 20-22 MPG. Tow a Rinker 260 Fiesta V. The 5.3 worked hard to pull the Rinker, 6.0 doesn't labor near as much. Ride of the 06 on 17" tires is way better than the 02. 6.0 doesn't use as much gas as the 5.3 does towing.