The reason it costs so much to remove a mouse from your vehicle though is because there are so many places a mouse can hide. Not only that, but the potential damage to your car is even greater. In the best case scenario, a mechanic has to disassemble your vehicle to an unknown extent, and then he has to put it back together again. In the worst case scenario, you're looking at the disassembly / reassembly, but also potential damage to wires, seals, belts, and other important components of your vehicle due to gnawing and nesting. This is an experience no car owner should have to deal with, but where there is food and shelter, there will be mice.
As I've said numerous times before, mice are looking for two primary things: food and shelter. If mice don't have a source of food, they will not stay for long. If they can't find an adequately safe place to nest, they will continue on their merry way. As fall approaches and it starts to get cooler, your car is a very attractive shelter. After being driven around for a period of time, your engine bay is an excellent source of warmth that lures mice toward it. Coupled with the fact that there are small, tight nooks and crannies for a mouse to hide in, it makes a perfect shelter. The other convenient thing about garages is that they tend to be attached to homes. As we all know, homes have food in them which satisfies the other requirement for mice to want to stick around. Your garage is like beach front property to a mouse. It's a perfect place to hide itself away and right next to the ultimate source of food. So what's it going to take to get rid of mice in your car?
If you're the kind of person who leaves old fast food packages on the floor of your car, you're just asking for trouble...
If you want to get rid of mice for good, you need to take away their food and shelter, or else they're going to just keep coming back. Start off by cleaning out your car. Do a thorough job to include vacuuming. It's great if you pick up the McDonald's wrappers, but if there are crumbs on the floor, that will be sufficient to keep the mice close at hand. Also, you need to lock up the food in your home and garage. A great supply of food for mice is pet food that is left in the typical paper bag packaging. Mice will chew right through it and have a lifetime supply of food at their disposal. Use sealable plastic containers. They even have big ones for big bags. This step alone will greatly reduce the risk of you getting mice. You also need to secure food in your home as well. If there is no food in your house and garage, the mice will just move on to your neighbors. When that happens, you can direct them to this site. :)
The other little trick you can do is to move your car. Mice tend to stick a localized area. They do not stray far from their nest. If you time it right, the mouse may be out foraging and when it comes back to where your car should be, it won't find it there. The key to this is that you have to move the car a sufficient distance from your original parking spot so the mouse can't smell it. Mice have an extremely acute sense of smell, and are known to make their way back home from miles away. Now I don't suggest you park five miles away and walk uphill both ways, but move your vehicle to the street instead of the garage. Where your car used to be parked, set a couple mouse traps and bait them with peanut butter. When the mouse is trying to go "home" in your car, it will find some food instead and hopefully meet its untimely demise. Also set a couple traps in and around your car. If the mouse is inside, and the car moves, it will have to come out eventually for food (assuming you successfully cleaned out your car). A hungry mouse is an easy mouse to catch, especially since you're going to provide easy access to a couple different food sources in the form of bait on a trap.
One possible side effect of moving your car out of the picture is that the mouse may migrate into your home. While undesirable, it is probably better than having the mouse as a resident of your car. It's a lot cheaper to call a mouse exterminator than it is to hire a mechanic to find a mouse that has wedged itself and gotten stuck.
If you follow these steps, you should be able to successfully get rid of mice in your car. If you're still having trouble with mice, then re-evaluate the surroundings. Remember that the best way to get rid of mice is to not get mice in the first place. Once you take care of your problem this year, remember to adequately prepare next year and maintain a clean garage and home so as not to attract mice in the future.
One final note... a mouse in your car could pose as a potentially hazardous situation that could be dangerous. Granted I haven't seen any recent news stories where mice have killed their hosts, but it is not something to be taken lightly. The integrity of your vehicle's operation could be compromised which may be a safety hazard. For example, a mouse could have chewed through the coating of wires and exposed a potential electrical hazard. This may result in a fire or other unexpected consequences. For this reason, it is recommended that you take your vehicle to a certified mechanic to be inspected for any possible damage.
If you have any questions or would like to share your experience with mice, please leave a note in the comments.
Best of luck in your mouse hunting adventures!