Prostreet slipstream help

[TruSake]

Whenever I play top speed and I'm behind a car, my car slows down from 200 to about 140, I thought that being behind a car was supposed to actually make the car go faster, matter of fact, the game itself gives a tip that if you stay behind the car you'd create a slipstream. What gives?
The only way I have found to avoid that is by staying on the edge of the road, but of course if I'm not careful I either end up going off road or hitting something that is off road.
Any other way to avoid such a horrible slow down?