I just bought a used 2006 Ram 2500 w/ a 5.7L hemi and 4WD. It seems to run just fine, and tows beautifully, but I'm only averaging 12 MPG unloaded and only about 7-8 MPG towing a large boat trailer (about 7,000 lb). The 4WD is useful on slippery boat ramps pulling up that big boat. Is this mileage typical for this year/model? If there is anything I can do to help the mileage, I'm open to suggestions.