I also was loosing the mice war. Traps, bait, etc. Then I put a sun powered mole chaser under the hood. This gizmo gives off a buzz like noise that almost sounds like a rattle snake. Every few minutes all night long. After two days no signs of mice under the hood. I would put the mole stake back out in the garden to do its thing during the day and to recharge the battery so it would run at night. Best of two worlds. Not moles in garden, no mice under hood of truck. Note: if you do this, place a note on the truck seat so you will not start up the motor sending the device into the fan.
Bob