Without any further ado (and after reading 4 pages):
Fallout doesn't need any cars/vehicles in it's current state.
The Fallout BGS presents us is an urban one. Means we don't even have enough travel-distance to have a useful vehicle system as of now.
Making it "useful" (and in this case I mean useful in the game, not for the players taste) we would need quite long distances with nearly nothing to do/show.
Also vehicle-combat would need to be done and so on.
As a story-driven sandbox game it wouldn't make much sense to have large empty areas. An example for large empty areas would be New Vegas.
And yes! I do use the http://www.nexusmods.com/newvegas/mods/49042/? in New Vegas, as well as the Verti-Bird version.
Like I said: New Vegas has long empty areas, wich makes this mod useful.
FO3 and FO4 (unconfirmed) don't really have a need for this, because the locations are nearly next to each other.
Therefore creating vehicles/ a drive system/ a gunner system/ fuel system/ additional npc behaviour/ ... would consume much time as well as a s**tload of money. And we are not talking about bottlecaps .
I am happy with what we get so far. For everything else we have the ability to mod the game.
And if you are not happy with what we get: Talk to BGS, they should hire Ermeso (creator of xre) as freelance dev (if this hasn't happened already).
This could make your vehicle dreams come true .