Comfortable Spot
The inside of the car explained the clear need to have a lot of warmth from the engine, and this, in return, creates a comfortable spot. However, wherever they choose to stay, they sure know how to create a lot of mess with nuts, leaves, and acorns they take in.
Danger
It may seem cute that they lodge in these places, but it can also be very dangerous. The Canadian Wildlife Federation noted the issue is serious and happens a lot in rural areas. The authorities noted the best way to decrease things like this from happening is to leave the boot open so the car can cool down and become less hot, and therefore less welcoming for wildlife.