Car engines
Any older car that does not have an electronic ignition system (a distributor instead), like my old Oldsmobile Delta 88, will work just fine and dandy without electronics. New cars will become pretty much useless.
It goes without saying that military systems are shielded against such things. Faraday cages can be redesigned for different frequencies, which is why your microwave oven doesn't cook you while you stand outside it.