there are two main types of air cars: Paragangaina and HomeWorld and they are very different.
[I always wanted an air car so this is a sort of wish fulfillment part of the story]
Paragangain air cars operate on reverse drive which is a type of Anti-gravity.
HomeWorld Air cars use living stone and thus will do much more for a chosen one than for anyone else.
HomeWorld air cars can be used to space travel they are fairly fast, perhaps slightly faster than space taxis, when driven by non-chosen when driven by a chosen one they are almost instantaneous travel [a form a dream travel, basically] and they can shape shift.