Alright. I read about half the thread before i decided to post so if any ideas i bring here have already been mentioned i appologise in advance.
With respect to the viable vechicle options: I belive it all depends primarily on how much time has gone by since the end of FO2, but assuming at least a decade has gone by, well.... In FO2 i delivered the vertibird plans to both the shi and the brotherhood. It wouldnt take 10 years for either of these 2 factions to manfacture vertibirds of their own. The only problem with vertibirds is that they are dependent on fossil fuels, and the known source for that was destroyed by you at the end of FO2. Still i would think since power armor is powered by a mini nuclear reactor ( if i remember correctly, and since your car runs on microfusion cells i would think that alternative fuel would be easily developed for the vertibirds. Now this doesnt mean that you'll be pimping around towns with your very own flying machine but they would be available for transportation at some point in the game. Now onto cars. The technology, fuel soruce, and resorces required to manufacture cars and motorised vechiles were present in FO2. As i said before they would run on electrical fuel. Vault City, with its vast computer mainframe woould no doubt have the techincal specifications of many vehicles, and the ever expanding ncr, would no dobut hava access to the respurces required to build them, and indeed they would find the need for motorised vehicles to increase proportionally to the ammount their territory increases. As for the tanker, nobody knows where it went, so it could have returned to san francisco or it could be half way to antarctica.
As for the setting of FO3. I belive north america has been played out. The story possiblities aren't too great. Another mutant uprising, ghoul uprising? thats boring. A story about untyting east and west united states perhaps....how exciting... Or maybe a band of raiders get ambitious about region control and happen to stumble upon a nuke and suddenly Fallout turns into an episode of 24. i dont think so. It's time to find out how the rest of the world was affected by the nuclear war, specifically what happened to the other old superpowers, like Russia and China. Now in FO2 the president gave me the impression that The US govt was the last remnant of the old governments still existent, but then again what would you expect for anyone so blindly patriotic, or from somoene who would exterminate a species of humans because their dna was different? It's quite possible that both the chineese and russians built vaults of their own housing their greatest minds and those deemed necesarry to their survival blah blah blah. And its also possible that these old powers would have the same aspirations as the enclave did. Initially i think the game should start somewhere on the west coast of the US or perhaps alaska but eventually a chain of events would drive the player to cross the ocean to siberia and that region of the world. As to how and why that would happen, i have a few story ideas but im not gonna mention them. Now china/ ruassia were just examiples that make sense to me but my point is i think its time we move away from the United states in FO3 and see what happened to other parts of the world. If the story does end up still centred upon united states i do see 1 possiblity for an interesting stoyline. The enclave wanted to cleanse the entire global population of mutated humans because there was a very significant change in their dna. The president mentioned that while there were little noticable differences ( i mean at a level where you could start distinguishing between them outside of a medical laboratory) between the mutated and non mutated humans at the time we dont know what atributes the mutated human stock would exibit in the future. Thats what fallout 3 could be partly about. Just an idea of course
EDIT IN:
Whooooops, according to the fallout bible it seems the russians didnt really do anything, but in fallout 2 the president refered to the enemy who launched the nukes against the US as the reds, and generally when i hear that i think of the russians, my bad