For severe rodent problems

Clean any existing debris In motor and use an enzyme neutralizing cleaner on any waste left by rodents (scents left in waste attract other rodents)

If possible clear the areas surrounding your vehicles. Rodents are far less likely to travel over open ground.

Do not use poisons! Poisons not only attract and kill rodents it also kills any predator or pet that eats them, making less natural deterrents for other rodents.