[KamperBob]

Originally Posted by slowmover

All corners and edges should be greatly radiused. My nine-and-half-foot tall 34' travel trailer had such, and wind just rolled off of it, instead of piling up against -- and pushing against -- the trailer wall edges and corners. I haven't found the source, but have seen quoted numerous times that a square box versus a rounded/aero trailer had road horsepower differences for the same speed of 50HP and 30HP respectively. AIRSTREAM maintains that their trailers take 20% less fuel to tow, all other things the same.
[/I]

The best travel trailer is an aerodynamic, all-aluminum, independently-suspended one. AIRSTREAM is the only survivor of that era. I averaged 13 on the backroads with my SILVER STREAK, and 15 mpg Interstate at 63 mph/ 1,850-rpm. Had I reduced to my current solo speed of 58-9 mph, I would (I believe) have broken 16-mpg (34' trailer). I am not alone at this. The "best" mpg appears to be, currently, with European turbodiesel SUV's pulling AIRSTREAM trailers at 16-mpg and better.

V8 diesels do poorly compared to 6's, but both benefit from many, many details related to hitch rigging, alignment, tires, etc, etc.

There is also a thriving breed of molded fiberglass trailers designed for towing by small vehicles. You can learn more here.
Egg Central

It depends on driving conditions and habits of course but I get anywhere from 15 to 18 mpg towing my 19' Scamp fifth wheel with a 4.7L 4WD Tundra for example.


Cheers
KB