I have your solution. Very simple and cost a lot less than a car capsule.
1. Obtain some nylon hoes. Unwashed but used/warn knee high is best. Cut off torso area if you can only obtain "panty hoes". All you need is one calf lenght piece.
2. Find a cat or cat owner. Unwashed cat is best. Washed cat owner is preferred, but not nessesary.
3. Aquire a BIG ball of cat hair through brushing of said cat and/or cat owner.
Cat owner hair will not work for this project.
4. Tie a knot in one end of nylon with the opening open. Creating a small pocket.
If nylons are provided by cat owner, remove nylons from cat owner first.
5. Stuff a decent amount of cat hair into opening, tie closed & cut off on far side of said knot.
You should have a little nylon ball of cat hair. About palm sized is good.
6. Repeat step five until you have 4-5 ***** of cat fur filled nylon *****.
7. Place the ***** in key locations of engine compartment and any other wiring harness locations.
Make as many cat hair ***** as you like.
It is the odor of a natural preditor that will keep the mice away.
The nylons just keeps the hair from getting messy and still allows the odor to easily get out.
And for what it is worth, the rats/mice eat wiring due to the insulation in wires.
Also, use traps in the storage bay, more cat ***** stuffed in any known openings, etc.
I hope this helps.