In your home, they are just a nuisance (and sometimes a health hazard). But in your car--you're talking about some serious repair bills--rodents cost one man over $25,000.
So here's a video with some good advice--I've checked it out.
In short, the video recommends:
- Closing all entry points to the house that are 1/4" or larger, especially where pipes enter.
- Controlling all food sources in your house, especially pet food.
This website has some sound advice and products for getting rid of mice.