They love the warm engine bays - my stepfather had a kitten when I was like 11 years old. He started the car up one day and heard these awful screeches - the kitten was in there. It ended up walking around the house with casts on both front legs for a while. After it got all nice and healed up, back into the engine it went, and this time didn't make it. Darwin at work; you'd think it would've learned the first time.