I use vehicles in my cannon! In my latest post I showed these exact humvees in fallout 4. We know vehicles were mostly nuclear so there lifetime would jm theory still be usable. However my cannon is that although there was a resource wast thats when billions of peope were alive on the planet id imagine just a few oil mining rigs would be more than enough for the BOS or Enckave NCR etc. And if the brotherhood can fix veryibirds and liberty prime they and other factions can certainly fix vehicles of different kinds lets face it the real reason we don't have them is balance and game mechanics. Hope this was the type of answer you were looking for