At 4-5 car lengths, chances are good that you were not slipstreaming him in the racecar sense, unless he has a huge Cd(big rear wing, some form of downforce on the rear) or you were literally inches from his bumper. I would think it came down to his automatic tranny, the TA's weight and general aerodynamics. The Camaro is more wedge shaped, so that helps, especially at high speeds. Either way, it's interesting that you were creeping back on him.