APT wrote:
10mpg sounds right for any high walled trailer and a gas engine. If power is not a problem as you claim, then maybe you are driving faster with the new truck. Since aerodynamic drag is the primary fuel cost, driving faster would cost more.
The OP stated he didn't see any mpg difference whether going 60 or 68 mph. I agree that wind resistance is the main culprit, so I'm a bit surprised by his statement.
I get 15 mpg with my 4 Runner running around solo. Maybe highest I've seen is close to 17 mpg when it was mostly highway. Towing I get about 7.5 - 8 mpg. I'd love to get 10mpg, especially in the Rockies.
To the OP, you have plenty of truck with that TT. Yes that 4.3 might have to work a little hard sometimes, but it's fine. Anyone who gets much more than 10 mpg towing a typical TT with typical frontal area, with ANY gas TV is smoking some good stuff.