I have an 04 Bounder 35 foot gasser with the vortec 8.1. we did 6500 miles cross country at various speeds and finished with an average of 7.3 mpg. we now tow a kia rio on a dolly total weight of 3000 additional pounds and we are averaging 6.8 to 7.0 mpg. As posted earlier, that vortec is a beast and not a thirsty one either. I don't see me getting a DP anytime soon.
Richie, Rose and our Australian Terrier Harley
2004 Bounder 35R, 2012 ACME EZtow,2012 Kia Rio Hatchback