Mint oil extract, they hate it, dryer sheets as well, they seem to work well in idle vehicles. Multi catch traps, the bucket with the dowel and can with peanut butter on it and ramp made of wood lathe or similar. I have used sunflower seeds floating on top, and just the ramp, but I think the can on the dowel that spins when it lands on it, dropping it into the water below is better for the mice, the seeds sink eventually and reek. That one does work well for chipmunks, just have to get that water level right.
The surrounding environment, clutter, piles of whatever you may have if there are any, food sources must be removed, as well as closing up entrance points.
The problem with vehicles is that they build a nest somewhere difficult to remove, that urine odor will remain and its a green light for them, an invitation for new ones, and there will always be new ones.
I have a ford ranger that was damaged, it had to sit, it got mice, and until I took the interior apart down to the firewall, and cleaned everything, they would come back, there was a nest I missed for years. I'm pretty good at taking apart and putting back interiors because of these pesky little pains in the @ss's. I closed off places they could hide, heat ducts inside, air breather intake, and kept dryer sheets in it etc. they have never came back to that truck as of date, same with my idle F150, they've never been in the cab at least. Just spread out a bunch of dryer sheets, replace every six months or so.
Vehicles, you will need to install hardware cloth somewhere in the air intake tube if so equipped, firewall, any holes in the trunk floor pan, interior floor pans etc. They got into the trunk of my cobra mustang one year, factory hole under the spare, just above the fuel tank, all it took was some hardware cloth in that hole to stop them.
My daily driver, they got in to the fresh air intake along the firewall, I took it apart and cleaned it up, one died of natural causes in the nest and it reeked terrible when I turned the A/C on ! Hardware cloth blocked that entrance. If you are sloppy in a vehicle, food crumbs, any garbage will draw them here, in just one night being parked ! I forgot something, a muffin or some baked good one night sure enough the next morning there was on in there.
You can make a huge dent in them by trapping however you do it, make it an all out assault, I have done it here with snap traps, 2 dozen total in a short time. I have recently trapped 17 from above my front door, the traps are now clean, but I hear one in 1 of 3 attics still, so I can't close that hole, or there is another entrance. I do now want them chewing their way out, soon as its clear, 2 small pieces of hardware cloth should be all I need, but I do need to check for more places they can get in, seems this is the only one unless I missed something and the first night I started trapping, soon as the trap was set, I'd go sit down and it goes off, 8 times that first night. I cram bits of a aromatic granola (Cascadian Farms or something like that, should be in the grocery store) into that metal bait holder, it lasts and they are attracted to it like crazy, the least amount in there will work. it crumble and leaves bits to draw them to the trap, I do this outside. One drawback is it will kill small birds, so put the trap in a tunnel or under something a bird won't see, find or be able to get to.
Lastly, stay on the program of trapping, even when you think they will be gone, sooner or later you'll encounter them again. Doing the above will definitely help, some places are just haven for them, and that has to change, I've seen it here and between 3 idle trucks, wood piles, they can get out of hand.
Cats definitely can work, but here they are just not enough and I have seen some unreal mousers, up close, incredible what they can do sometimes. Problem here is they like voles too, but they are no problem, as they do not behave like deer or white footed mice, can't climb as well and rarely if ever get inside the house, I did have some years ago, found a container of old bird seed that was forgotten or left by someone other than I.