STBRetired wrote:
I have a 38ft Class A with the V10 and a 4 speed trans and averaged 6.8 MPG from Chicago to Florida and back last year running 65 MPH towing a Chevy Malibu. I would expect you to get better mileage with the 5 speed.
The new 6 speed might get somewhat better gas mileage. The 5 speed probably wouldn't do noticeably better, all other things being equal, because the ratios of the top three gears are exactly the same as the 4 speed. (The extra gear is added between first and second, in other words.) In practice, it might do slightly better due to more clever programming of the computer controls for the transmission and engine.
7 mpg would be a reasonable estimate for the original poster, I think, depending in large part on how fast they drive.