by then the internal combustion engine will be gone for sure.. that'll be sad. people will live thier entire lives not ever hearing the pur of a well tuned engine... there will surely still be performance oriented vehicles, whatever fuel/energy system they use, but they just won't be the same.
i'm guessing electric and fuel cell powered vehicles in 100 years, nothing that much different than those - maybe hydrogen? or maybe an electric/fuel cell hybrid. really i don't know anything about how any of these systems work. but i'd imagine at least electric motors would be harder to modify and improve.. unless you want to replace the whole motor