And agreed. There is aerodynamic turbulence and thus drag at both ends of a car. In two-car drafting, the lead car absorbs most or all of the front-end turbulence, but the rear car absorbs a significant amount of the rear-end turbulence, so the drag is shared between the two vehicles. Obviously a car doesn't alleviate much of a semi-trailer's drag. But it certainly doesn't *add* to the semi's load. The turbulence the drafting car takes advantage of was already there regardless.

All through threads where unusually responsible and respectful truckers tell us not to draft, tailgate, etc., I've been practically swallowing my tongue anyway. Guess what: when *I* run 10 feet off someone's bumper at 70 mph (five over the limit) in a 2,900 lb car, I have at least a reasonable chance of not rear-ending them if they brake unexpectedly. I see 25-ton trucks doing this *all the time* -- with each other, with tiny economy cars, with anyone who annoys them or puts them at risk of actually having to hit the brakes -- and I don't really need an admittedly nice and responsible but *extremely rare* trucker lecturing me about "safe" following distances. A lot of those guys drive like total jerks a lot of the time, and the only thing that keeps them out of trouble most of the time is vast experience and superb judgment about what they can, and can't, usually get away with.

There are a lot of good reasons not to draft a big truck too closely. But I don't need to hear it from them until they clean up their own act, which will never happen.

--d