from sleeping overnight on a warm truck motor?
Either cool off the motor engine, leave the hood up (maybe) or Garage your
vehicle.... Everyone likes a bit of comfort! Maybe give them another warm place to be instead.......Hope you solve the problem.....soooooon.......
Got a car alarm? Is it adjustable in its sensitivity? I'd use that to scare them. If not how about a fog horn? They like their privacy so if ya scare them a couple of times they'll go away. How about a motion detecting light somewhere near the car?
It is a very good idea to slap the hood and front fenders before starting a car, or truck . Cats , squirrels, toddlers etc. like the secrecy of the hiding spot. The life you save is worth the time to tap.
Spray with deer off !! Smells like urine and they will look for another home quick!!