[joegoeny]

Actualy your cranked Ford model t comes emp hardened. Your 60s muscle cars willl need a backup set of wiring starter motor, spark plugs etc stored in a faraday cage.

[Garth Tater]

If it doesn't have any electronic components in it your car will be fine. Even in more modern vehicles the electronics will probably survive though they might need to be reset.

EMP Effects on Vehicles

"Automobiles were subjected to EMP environments under both engine turned off and engine turned on conditions. No effects were subsequently observed in those automobiles that were not turned on during EMP exposure. The most serious effect observed on running automobiles was that the motors in three cars stopped at field strengths of approximately 30 kV/m or above. In an actual EMP exposure, these vehicles would glide to a stop and require the driver to restart them. Electronics in the dashboard of one automobile were damaged and required repair. Other effects were relatively minor. Twenty-five automobiles exhibited malfunctions that could be considered only a nuisance (e.g., blinking dashboard lights) and did not require driver intervention to correct. Eight of the 37 cars tested did not exhibit any anomalous response."