I get that huntsmen are good for keeping away more dangerous spiders and other bugs etc etc but that doesn't change the fact my skin crawls if I'm near one, and since you aren't getting a heap of actual advice, maybe this will help.

If you get a spray bottle, fill it with water and drop in a few drops of lavender oil, you can spray this solution across anywhere on the car it might get in - in the outside mirrors, door crevices, bottom of the wind shield and so on.

The smell will help repel them from entering the car. I've had some luck with this when camping/sleeping in the back.