Purchase a plastic toy of a dragon, dinosaur or other fierce beast. Make sure its mouth is open, showing lots of wicked teeth.
You may want to charge it first, by holding it in your hand, visualizing it fiercely protecting your vehicle from accidents, theft and vandalizing. Say an appropriate invocation to your god or goddess if applicable (for instance, if you are using a cat or lion toy, you may want to invoke Bast).
If you hang this in your windshield, it will fiercely protect your vehicle.