If it is powerful to fry electric cars it will also probably fry the computers in gas ones too.
In that case only cars made before circa 1992 will work. (This was a plot point in the Tom Cruise version of War of the Worlds.)
Actual testing showed most cars are not impacted beyond messed up lights on the dashboard. The only car that was killed by the EMP test was Saturn b/c it’s mostly a plastic body. Normal cars’ bodies act as crude Faraday cages to shield most of the effects of the EMP.