Maybe, but maybe if the worldspace presented in the current games were larger and some details are taken into account, it may work. Filling a larger world with plenty of content and worldbuilding is a prospect in itself, but putting working vehicles into the mix and making it work is something else.
The worldspace may be big, but making sure the world isn't just a set of towns with shops and a population of randomly generated nobodies with only two or more lines of dialogue makes for a living world, or at least what's close to it, but I digress...
If we're talking problems regarding fast travel, certainly I feel the mechanic seems more of a convenience, and less from an immersion standpoint. A convenience for the players and devs alike. Its existence alone, especially in Fallout, prevents more creative stuff from actually thriving.
Why bother going on a train ride to a major city, when you can just fast travel? Why bother gathering parts for a Highwayman and the fuel needed to power it, when you can just fast travel? Why bother going on a lone walk like a lone wanderer or sole survivor, when you can just fast travel?
I guess the only way working vehicles as a faster travelling option in Fallout can work and be a viable thing is if the ability to fast travel is removed entirely. To my eyes, getting rid of it and nothing significant changes for the worse, aside from perhaps adding more to your playtime.