As Joe suggested, cats are good, but, you have to feed them as well.
One can set mouse traps around the car and check every couple days. I use Swiss cheese.
If you're one who uses jack stands to remove the weight from the springs, my suggestion would be to place old cake pans, pie tins, alum sheet, etc. between the jack stand and car. Place the pan upside down. This way the mouse can't crawl out to the end, and can't crawl up the sides.
Everett "OBJECTS IN THE MIRROR DISAPPEAR UPON RAPID ACCELERATION"