I saw those mythbusters episodes. i liked the one on drafting. I tried it some and you'd be suprized how far back you can sit and still get benefit, without alot of buffetting and without risking your hide. I could pace the truck at a safe distance and would hear the motor running at lower rpms. There is a point of diminishing returns due to turbulance, though.
I thought the blowout episode was misleading and dangerous, because it gave folks the idea that it's not a concern. They were testing sudden, catastrophic failures only. Now, I've seen tires on trucks fail at speed which did NOT involve a blowout. The tire just starts to fall apart. Like it or not, if you ride near a truck and that happens, you do risk having to dodge large pieces of rubber at highway speeds, which can take you out. that myth was far from "busted" and as a rule I stay away from trucks on the highway. you'll do what you feel safe doing, but I wouldn't put my life in the hands of the "Mythbusters"......