There will be a time when internal-combustion engines become a rare sight on our roads. The question remains, though: What do we do with all of the classic enthusiasts' cars that are still around? Will they gather dust in museums and private garages, only being trotted out for the occasional show so the public can gawk at the transportation of a bygone era? Or can they be updated, their hydrocarbon-drinking innards gutted, and replaced with silent running electronics?