EcoBullet wrote:
Fuel economy while towing travel trailers is much more about frontal area wind resistance than weight.
x2. I have a 7x14 cargo trailer loaded weight 6,000 lbs and a 35' outback close to 10k loaded. 7x14 has noticeably less frontal area. However the difference in towing them over the same route is less than 1mpg on level roads and between 1 and 1.5mpg over hills. I suspect if they both had the same frontal area (two similar TT), the mileage difference would be even less.
weight comes into play on hills and on accelerating. For practical purposes weight is a non effect at steady speed on level ground. It has a minor effect on rolling resistance and a few other things but frontal area and wind drag dominate.
The Hybrid pop ups are an entirely different story. with dramatically lower frontal area hidden by the TV, the mileage hit vs. unloaded is much lower. We have friends with a trailmanor and fuel economy is much better.