It is interesting, but not surprising. Weight doesn't make that much difference.

My 16TBS probably weighs at least 50% more than an a CL 11 but I get about the same mileage as rideandfly.

But the QS8 with its low profile (and lighter weight still) gets in the upper 20s.

Frontal area makes all of the difference. If you could tow an inflated bounce house and it would get horrible mileage.

David

To get a little nerdy, you can estimate fuel consumption impacts from the following:

Rolling Resistance + (Weight x Hill_Grade) + (Weight x Acceleration) + Wind Drag

Rolling Resistance is basically a constant. Can't do much but use low rolling resistance tires like hybrids and electric cars often use.

Weight*Hill_Grade theoretically cancels out on a round trip since you go up and down hill

Weight*Acceleration is a factor, but you have to accelerate up to the speed you want to drive, so the only thing you can do is keep your weight down.

Wind drag is the big one. It's a function of the coefficient of drag (Cd) and Speed Squared (Speed x Speed). The Cd of a Camplite is much much higher than a Quicksilver. And small changes in speed make a huge difference since it's squared -- for example, the difference in fuel used due to drag when you drive 75 mph versus 50 mph would be 1.5 x 1.5 or 2.25 the fuel needed to overcome drag.