A car can protect you somewhat from a lightning storm as long as you don't touch any metal parts of the car during the lightning storm.
Although if possible get to someplace where you can get inside a building such as a restroom alongside the road or into a convenience store or other store you're near.
Only stay in the car during the lightning storm if you have no other options otherwise get somewhere where you can be inside a building during the lightning storm because lightning can still strike a car and strike you through the car in rare cases.