I get combined 15.1 mpg towing it with a Toyota V6 from Lake Tahoe to the Arizona high country and back. There's lots of rolling hill desert and some serious uphill climbs/descents going both directions. I have a manual transmission and wouldn't have it any other way.
Randy, you seriously ought to consider and compare a lightweight travel trailer rig against a Class C. If you truly need something heavy like a Class C, I merely recommend diesel power.
Thank You to all the great suggestions!
What kind would you suggest and what are YOU using now?