If possible, use those pet and kid friendly bait stations outside, around the building where you are storing the vehicle. The best defense, is a good offense. IF you are going to use the snap traps, resist the urge to lather the lure with bait. A little dab of peanut butter or nutella will do it, especially on the underside of the lure. You want them to engage with the trap, otherwise they can sit pretty still and eat their fill.
Try to keep trash and any kind of food out of the area you store the car. Aside from looking for shelter you don't want anything additional to draw them inside.
For the nuclear, trap option, I have heard that this thing works real well. But for the price, it might as well wash and wax your rig and make lunch.
The Goodnature A24 Automatic Rat and Mouse Trap is a revolution in humane rodent control. Its superb engineering and rugged design make it the perfect rat and mouse trap for inside or outside your home or business. The A24 trap automatically kills up to 24 rats or mice with just one CO2...
www.acehardware.com
Good luck.