The is aproduct callled Cab Fresh that I use.
It is small packets of smelly stuff that is suppose to and seems to keep mice away.
Two packets in the combine and grain truck every fall for 5 years now and no more mice.
Had them before that.
Comes in a yellow box with red writing at Theisens and the such. 4 packets in a box.
My son uinlaw swears by dryer softer sheets for his old truck.