We have a Cruise Master class A on a version of that chassis. We do have a Banks performance package on ours and it is a 35', 18K# motorhome. We get about 8.5mpg over all and most of that is towing a CR-V. We drive about 58mph. Speed is a key part of mileage. Each 5mph you increse speed above 55 will cost you about 10% decrease in mpg.
The only data that I have accumulated on our Class C V10 is on a trip we took to Colorado where we had a schedule to keep. You can check out Kirk's formula, but it looks to be accurate. We tried to maintain (with cruise) an rpm of 2500 (a speed of 65 mph). Our best mileage on flat freeway was 8.2 mpg. However, a stretch with strong headwinds reduced mileage to around 6.0 mpg (the worst). We averaged a speed of 52 mph.
I'm inclined to believe that engine manufacturers have chosen 2000 rpm as the "normal" driving rpm. On the vehicles that I have, that will equal 55 mph to 60 mph.
At today's prices ... I'd rather be _park_ed! :approve:
I have a '99 Vanguard VXL 2000 with the Ford 6.8L V10 in it and it has been getting 10mpg in the city and 11-12 on the highway. I also drive fairly fast when on the highway, usually 65-75mph/110-120kph so I'm sure I could get 13-14 if I was much more conservative on the gas pedal.
Yes, speed is key. When I was pulling my 5ver at the speed limit (70 - 75 MPH), I got 8.2 MPG on average. Slowing down to 55 MPH, I got 10.2 MPG on average. Also, was a lot less stressful (for me at least; can't say about the people behind me )
I had a 1999 32 foot Holiday Rambler Vacationier with the V10 and the Banks system. I got about 8 MPG pulling a Jeep. In 2000 Ford changed the head and exhaust design to up the HP from 275 to 300. So, info on 2000 years and later may differ.
BTW, I also installed a Gear Vender under/over drive. The trans on the Ford sucks. There is 1,300 RPM difference between second and third gears. It was not able to pull hills with a load. The inbetween gears helped a lot.
I guess my ole Winn Chieftain doesn't do so good on gas milage. It has the 454 (only have 15,000 miles on the 1989) and get about 6-7 MPG while pulling tow dolly w/Mitsubishi Diamante. I'll be replacing plugs and wires soon (just because of age not milage), gas filters (both) and see if it helps a little bit next time I'm on the road. hate to think what it is gonna cost me next fall on trip to Florida for the winter.... :dead: