I think I scared him off. I hope not. I was only playing with him. If he comes back I'll welcome him to the forum.
He's talking about stuff like belly skirts or those funny looking things on the back of van trailers. I'm actually interested in seeing some actual 3rd party numbers about how much fuel is actually saved. And I understand how vortex generators can increase the speed or fuel efficiency of aircraft, but though I've been seeing them on trucks lately, I don't know how well they work.
Can't trust the tree huggers or the actual manufacturers of those things to give honest numbers, gotta go with what the fleets are seeing themselves.