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About vehicles I definitely think there should be some, if in Fallout 2 we have a working Highwayman and a mechanic that knows how to restore pre-war cars with the right tools, parts and financial incentive. I don't see why there shouldn't be more people who know how to repair vehicles, Fallout Tactics (although Semi-Canon) also has working vehicles (and it would make sense that the BoS would collect vehicles and restore them, after all those are also technology and the BoS has plenty of records and manuals and plenty of scribes that learn all kinds of tech and repair skills and all of that stuff).
The thing that would make it limited is the fact that most pre-war vehicles run on fossil fuels that are pretty much depleted (Anchorage is one of the last oil deposits in the world). But now all of these factions use vertibirds (Enclave, NCR, BoS), the Boomers could restore a bomber and fuel it with bio-fuel made from corn, The Shi think they can make and fuel a spaceship in a few years after Fallout 2, Mr House also believes he can do that with time. So I don't see the fuel being a problem anymore.
Imagine the whole point of a Fallout game where some new faction was invading the wasteland and their biggest trump card was pre-war military vehicles that were altered to run on bio-fuel and/or electricity. During the past they would have been collecting vehicles and studying ways to make them work again, training drivers and soldiers, building a large stock of fuel and generators, etc. After decades they finally got enough operational vehicles and manpower to start taking on the wasteland.
Most of the pre-war helicopters and planes were grounded because of not having enough fuel (this is canon), most heavy military vehicles like Tanks and armored troop transports suffered the same fate, now imagine that some people found a huge underground depot full of those grounded vehicles with their assembly plans, plans on how to refit them to be able to use different sources of fuel (which IIRC is canon that military scientists were starting to study on how to do that before the bombs fell), training and usage manuals, etc.
To get an idea, these are pictures of WWII vehicle boneyards (imagine something like this but underground, because they weren't supposed to be abandoned, they were supposed to be refitted to be operational and on the war front again by the USA):