Practically speaking, vehicles would have to be super-rare, and not like Fallout Tactics where you happened to have a few spare cars in the garage for whatever suited the occasion. The entire issue of the war was fuel, after all. At least the Highwayman was slightly intune with the environment since it ran on fusion cells (and don't forget the opening cinematic in the first Fallout showing off a shiny Highwayman for the price of a king's ransom).
But speaking on a personal viewpoint, I'd want a vehicle that has character. Something badass like a Harley. Or an ugly retro monster reminiscent of Road Warrior. If I'm the hero (Vault Dweller, Chosen One, whatever) I want something that's *boss*.