[quote=@Apollosarcher]
[@mattmanganon] Three to four weeks is without roads, it would take months on horses. You can get across country now in six days currently it's not a stretch that without roads you could manage it in a month. Plenty of military vehicles laying around unused so off roaders would be easy to acquire.[/quote]

Yes, but you need to remember that just because they were designed for these conditions, doesn't mean that they are completely immune to them. And if the military vehicles are anything like modern day ones, then they are designed to withstand the harshest of terrains in short bursts. Going for a week, then having to be completely overhauled... And that's assuming that everything went as well as it possibly could, with the best engineers in the world at your beck and call... These conditions are completely different.

You have engineers that have never seen this kind of equipment, combined with the fact that it's all been 200 years without maintainance, combined with the fact that all of the parts on military vehicles are generally specialized, designed so that enemies will have an extraordinarily hard time repairing/maintaining them if captured, but allies just need to ring the supply office and have a box of them sent. It's alright for NCR/Enclave/Brotherhood, because they have VR training pods, as well as access to a vast quantity of military facilities, in which, parts will be lying around, as well as production facilities where the schematics will be. But, long range and with no chance of back-up, I don't see that working.

Honestly, the way I see it, if they try taking a military vehicle across the country, I imagine that 90% of the trip will be spent scrounging for parts when things go wrong, having to find a new vehicle because they can't figure out what is wrong with that one, then scrounging for parts for that as well. And don't even get me started on Raiders/Supermutants/Slavers/Enclave/Legion taking potshots at you as you drive past, causing further damage to the vehicle.

Don't get me wrong, getting across the country is far from impossible, again, if our good friend Harold could do it with most of his brain missing, then I'm sure that any idiot that set his mind to it could do so. But I think that 3-4 weeks across harsh terrain and everything and its mum trying to kill/eat you is a VERY optimistic. 3-4 months I'd say is more reasonable.