Highly recommend the car-bag. It is really thick plastic so it would be tough for mice to chew through (although I'm sure not impossible)
Here are the 2 examples (as I said I bought the cheaper one.)
http://www.autoanything.com/car-covers/20A50302A1.aspx
The only negatives are the length and the zipper gets caught but if you go slow its fine ( really slow ). Also storage of it is a little tough. It rolls up into about 7' long and about 2' in diameter.