There's already one like that; it's called the Tesla Roadster- although it's not really a brushless motor, but an induction motor (so yeah, a type of brushless I guess?). Lotus helped to design the car in fact (and that is why it resembles the Elise or Exige to a certain extent). And to top it off, it's powered by A123 cells! The battery pack alone weighs about 900 lbs.

Too bad it's also a 150,000 dollar car....