On the main menu, there should be a new button called "vehicle editor". When chosen, it brings you to a new map, 16x16 (or whatever size) and you design a car, plane, or w/e. There are all the normal blocks plus a new "seat" block (just a normal block with a different tex.). After building your vehicle you can use it in-game by standing on the seat and pressing a button, then you control the vehicle instead of yourself. In the vehicle customizer, there is an option to make it "flying", or "ground vehicle".
I really really hope you add this to the game!!
cubelands evil commented
God Creator commented
yes oh yes :D
sounds very interesting