Dumb luck.
(with bad sight and bad aim, I scored the bull's eye with pneumatic gun, not because of aim, but because from all the probable places within and outside the target the bullet could hit, it hit just that one)

I thought it could've been aerodynamics effect (so air slows you down more when you get closer and less when further) but that's not it - it would work the other way around (closer you "glide the wave", less air resistance because the air is on the move, propelled by the first car, further you must fight all the "standard" air resistance, so you fall back... unless that DOES somehow influence the system, through software i.e. less air flux = less power to the engine = speed falling)?