Yes, it is completely safe as the rubber from the tires isolates the lightning. You will be safe as long as all doors and windows are completely shut. Make sure you do not have anything hanging out of the car, or even any issues on the glasses, such as cracks, otherwise you will not really be safe.
I had seen some videos the lightning strikes on one car. It starts to explode. The car is in the middle of a field. I haven't seen a car that was struck by a lightning in busy streets or cities. I think the lighting strikes anywhere and it is so frightening. That is why everyone to be inside their home or a building. The lighting could strike anywhere.
There was a video that the lightning strikes a car that was moving. It was all sudden and the lightning even left a crater in the ground. The passenger of the car said it was difficult to breathe inside. The two-passenger knows that will die in a moment. They know they will not come out of the car alive, but then there is someone who rescued them. If you watch the video it is really impossible to survive the blast but then to their surprise they just celebrate their 47-year anniversary. Too good that there are people who saved them. Lightning strikes anywhere, but it does not strike the same place twice as they said.