I didn't think there was a such implementation of slipstream in the game. For you racing rookies, I guess I'll explain what I'm talking about.
-THE CONCEPT OF DRAFTING-
When race cars zoom down a track, the cars generate a good deal of turbulence. The higher the speed, the more the turbulence. When a car behind another tends to get sucked into the slipstream of another car, it has a sort of vacuum effect. When the racer behind gets just enough pull from the other car's slipstream, the trailing racer can easily zoom past the car ahead with the slingshot. Drafting is simply when you have one racer ahead at speed and has a sort of turbulence that suddenly pulls you win. And when you have enough turbulence, you can inch closer and closer until you simply blow past the car ahead. The slipstream is that turbulence behind a leading car.
Or set me straight if I'm wrong. It should probably be one of the simplest concepts race drivers and fans should know. Maybe that is why I didn't drive so well at normal difficulty in GT's arcade mode- not learning about the draft. Perhaps my worst moment in my racing game history involving draft has to be the arcade game "NASCAR Racing." I raced the Talladega track in the arcade game, and while starting 40th... I STAYED there! Couldn't generate any sort of draft to bypass the other AI racers, and if this is also in GT4, I'm going to be spending a lot of time trying to learn how to win races.