Eli5. Why do tractor trailers put cardboard in front of their grill in cold weather?

Question

Do diesels need more heat to operate? How do they differ from gas engines?

In: 3

Answer 1

Cardboard on grills limit amount of cold air into engine compartment, keeping what’s under the hood hotter, to allow the cab to be warmer… furthermore – it protects from winter elements damaging the parts under the hood.

Edit: more info