Car electronics affected by coronal mass ejections?

It would be theoretically possible, I suppose, but highly unlikely. A CME and an extreme magnetic storm can induce high electrical voltages, but the length of the average car wire isn't long enough to cause much of a problem. An AM radio transmitting antenna tower perhaps, but not a car's AM reception antenna. Power wires strung for miles from city to city, sure, but not a wire from your battery to the taillight.

There are a great number of things that we need to worry about each day. I would rank this one pretty close to the bottom of the list.