Thor Forums

[Chance]

A little reverse engineering can give a rough estimate. A compact motorhome will use around 100 HP to cruise at highway speed, and the rolling resistance of a 4,000-pound toad should be around 7 HP at same speed -- more or less depending on speed and tire quality (low-rolling-resistance versus standard).

For a motorhome that gets around 8-1/2 to 9 MPG, that extra load should represent about 1/2 MPG penalty. A lighter car would be proportionally less.

My guess is that most of us drive a little slower and more conservatively when towing (whether trailer or toad), which would make the difference less than 1/2 MPG.

Owners who pull Jeeps which have off-road tires probably take a greater hit because off-road tires generally have greater rolling resistance. The difference compared to modern low-rolling-resistance tires can be significant.