I went on Ebay and bought some cheap plastic boxes and some magnets and made these and put them under the hood. We'll see how they work.

 

A month of dryer sheets under the seats, mothballs on the tires and under the hood and spray containing peppermint oil and no sign of any mice. Must be more than luck because the local garage has 4 cars with electrical damage due to them. Only downside is the mothball smell.