More to drafting than staying close to the vehicle (and in danger). When behind a slow vehicle, drop back before passing, when you are ready to pass, speed up, (that is at the proper time) and then pass the vehicle when you have a nice head of speed. This depends a bit on knowing the road.
Learned this driving a 240 ci Ford Pickup... and it works well on a WRR250R too.
"I don't really know, I've been too busy falling down."