MacGregorSailors.com

Pretty sure I posted this at the time, but last summer I did two trips to the cape from ALbany and, for fun, did one at 70 mph on cruise and one at 60 mph on cruise. Tow rig is a 2002 VW Eurovan 210 HP 6 cylinder

Since air resistance goes as v^2 I thought I would enjoy a cool (6/7)^2 or approximately 0.7347 (rounded to the nearest harmonic of PI) fuel consumption advantage at 60 mph...

I got exactly the same (13 mpg IIRC) of course.

Since air resistance goes as v^2 I thought I would enjoy a cool (6/7)^2 or approximately 0.7347 (rounded to the nearest harmonic of PI) fuel consumption advantage at 60 mph...

This would only be true if wind resistance were the only component. It's not. For normal sized vehicle with typically, lots of excess HP, it's a dominant factor as speeds increase. But when pulling a heavy trailer up and down hills, it's less dominant. Besides, there are lots of other confounding factors which make measuring gas mileage even on consecutive trips over the same route, problematic. Here' one of them: The difference between a 5mph headwind and a 5mph trailwind is - drum roll - 10 mph. Ditto dead calm compared to 10mph wind. That rate of wind speed is not uncommon and can totally neutralize the speed factor. Or make it way worse, depending.