Maglev Vehicle Racing

There would be a halfpipe-like Maglev track that's a mile (At least) long. People would build their own aerodynamic vehicles, and then figure out what type of propulsion they would use: Rocket, jet engine, prop, etc. A mile might not be long enough, people could easily top a hundred milesper hour, maybe even two hundred (With a jet or a rocket). Maybe make the track five miles long, hit a turn (A BIG turn, with banked sides, to minimize g-force), have a multiple lane track? Anyway, besides the humungous cost, the chance of someone becoming airborne, and where I could construct a perfectly flat track, what else did I not consider?