Actually the car body acts as a Faraday cage.
http://en.wikipedia.org/wiki/Faraday_cage
≤}B^)
In 1992, I was driving down the Baker Grade, north of Baker, in San Bernardino County, Calif. into a storm. Ahead of me, lightning strikes were happening one after another--it seemed as there was one every few seconds. However, I got through the storm all right and stopped for a baklava and some Middle Eastern coffee at the Mad Greek in Baker. The previous day, I had driven under a funnel cloud at Mountain Pass, about 10 miles north of the Baker Grade.