I have to agree with Sendler and Redpoint5 (Alpha Golf Hotel India Delta?).
And I'd like to mention a few thoughts;
1) Large trucks have a lot of mass. Should something happen instantly in front of them, I feel safer letting that mass plow its way through, clearing the road for me.
2) Ladders, exploding tires, lumber, animals... are all road hazards that could become real problems if one is not quick on the draw. Drafting not only requires paying attention to the rig in front, but as usual one should pay attention to everything -around- your vehicle, should there be a need for a hard-bank-left to dodge something the rig could not get out of the way. *Defensive Driving - do you know how much you can turn the wheels going 60mph without flipping your vehicle? I do.
3) When I drive interstate, I usually install my Uniden Grant CB radio to chat with truckers on the long drive. With that I can ask them if it's okay to draft them so I can save gas. Most say it's fine with them, some ask me not to and I move on.
4) The images here of the aerodynamics and wind resistance are a big help visually, but keep in mind that we're living in a 3-D world filled with randomness. For anyone who drives a light weight vehicle and tries to draft a big rig should know there is a point where all the lines in the images do come together quite violently. The turbulence just before you get to that smooth 'sweet spot' is like a whale's tail; trying to fish-slap your car off the road. There's a similar area near the driver's and passenger's doors as you try to pass one - the deflected wind from the front of the rig is pushed off to the sides. You will notice your car getting a bump away from the rig when you get to these areas.
5) I will NOT draft other cars and trucks on the road - mainly because these regular drivers know nothing about aerodynamics and proper drafting, most flat-out don't know how to drive (defensively), and as I mentioned above, there's just not enough mass for me to feel safe driving that close to them.
The End.
lol