1.) Hav-a-Heart trap, baited with Doritos, under the car engine every evening. In the morning you can drop the inhabitants near the car dealership.
2.) Rent a weasel. We had one in the house once, and I could hear it chasing mice. It didn't stay long, but neither did the mice. (If one lives in a Maine farmhouse that's nearly 150 years old, one gets used to neighbors of the furry kind.)
Best of luck. Our daughter-in-law had the same problem this past summer; they used regular spring traps, but it was a few days before they got both (all?) the mice.