First off, they are a *itch to cut off those moths!
But seriously, carefully look around the storage area for EVERY POSSIBLE ENTRY POINT that you would even think a mouse could get into...then set the moth-ball(s)/cakes near that point. DON'T STICK THE THINGS IN YOUR CAR. Someone will think you're hiding an old, dead, relative in the trunk!
Then, set a ball/cake near each tire...mice will always use your tires to climb up, and into, the car frame from that location.
If you have the car plugged into a "trickle charger" or any external item is connected to the car, set a ball/cake at the point where the item is either leaving the floor and up to the car, or in a container near the point where the item reaches the car. Don't let the ball/cake pieces touch your car. There's a chance that the fumes that eminate from the ball/cake will create issues with the vehicle's paint/trim pieces.
I never thought that moth cakes/balls would work, but here's a little testimonial to their effectiveness.
I have a little 50-Watt FM translator that I take care of, located in a "public" shelter...it sits, locked in a small metal cabinet that is mounted about 15 feet up on a wall. The first time I ever looked at this thing, it was covered and stained w/about 5 years of mouse dung/urine. I removed it from the cabinet, took it to the house, and out in the back yard, I literally HOSED it down, DE-NATURED ALCOHOL bathed it, then I sprayed it with the "Fabreeze" crap...let it sit for two days in the garage, then I washed it down once more with the hose, then rinsed it with distilled water. When it was done dripping, I spent two hours pulling every board and dial that I could and I hit everything with a hair dryer.
When I returned to the shelter, I went through 2 rolls of paper-towels, a bottle of '409' and DOW 'SCRUBBING BUBBLES' Bathroom cleaner spray (This stuff cuts tobacco smoke tar from surfaces better than anything I've ever used in my life!) before I put that radio back in the cabinet. THEN, I took a "suet feeder" that I bought from the local ACE HARDWARE, and I inserted a "Moth Cake" into it.
Every three months, I go back to the cabinet and when I open it, all I remove from the cabinet and radio transmitter now is dust. Even the wasp nest that I pulled out of there hasn't returned. I check the cake, and if it needs to be, I replace it with a new one. ($0.89/cake)
Moth Cake/Moth Balls - You hate the smell, but there are other things that hate it worse than you. But isn't that why you love it?