The Feds using our hard earned tax dollars have throughly studied truck/trailer dynamics with an eye towards decreasing fuel usage and recommended that truck trailers be required to have a “boat tail” on rear end to improve the aerodynamics. http://www.greencarcongress.com/2006/11/study_improveme.html
Funny you should mention this. I recall “drafting” a semi at 75mph between Staunton, VA and Washington, DC.
Dunno about fuel economy, but it cut wind noise significantly.
Totally agree! I remember when I was drafted, not a single draftee was in drag!
I’m surprised (happily) that you lived through the event. Do you engage in kamikaze driving often? 
DON’T DO THIS!!!
Tailgating is one of the biggest causes of accidents.
The tiny amount you save in fuel will be lost when you have to pay for the damage to both vehicles.
Mythbusters proved it works, but the distance it works at is so short as to make it very dangerous.
NASCAR is also known for crashes, and most of them are caused by getting too close.
Can you reply? Related question…Since I like to go the speed limit and that generally means everyone passes me, is there a benefit from semis passing me and “pulling” me along for a moment or two???