
Another thing to be sure to do is eliminate any potential food or water sources for them like stored pet food, trash or wrappers. But, I'm sure your garage, like ours, is pristine like a NASCAR team garage, right?

If you were much closer I would just drop off two of my cats in your garage for a weekend (gotta keep the third back-up cat, just in case). Although they spent their first year indoors, they have become real killers in the neighborhood. Within minutes of letting them out in the morning they offer "presents."
Mice caused a couple hundred dollars damage to our lawn tractor, so I can sympathize. That's why the cats now get to go visit the garage.
Good luck!