I guess it's going to depend if the needed parts are going to be obtainable. It might make sense to purchase an entire junked vehicle just for the parts, or to have two of the same vehicle and plan on cannibalizing one vehicle to keep one running. Two is one, one is none. Also plan on alternative modes of transportation, i.e., bicycle, horse, or shank's mare. A good mechanic can perhaps fabricate a needed part, or maybe not. Modern vehicles have become so complex, that it sucks for the home mechanic. I can still repair our Jeep, but there's no way I could make a major repair on my wife's car, it's just too complex. If those two vehicles broke down, I'd have to resort to using the Ural motorcycle, which is based upon a WWII BMW design, so it would be repairable in Mad Max conditions.
