the french company mdi licenses its air cars, using cat [compressed air technology] as energy storage.
using bi-energy [compressed air + fuel] the cat vehicles have a driving range of 2000 km with zero pollution in cities and considerably reduced pollution outside urban areas. refueled in three to four minutes. indian tata motors aims at producing around 6.000 mono- and bi-energy onecat air cars at €2.500 by 2008.
watch a video. read a wiki on air cars.