Purpose in covering?
My guess is:
Dusterdeere lives in a serious snowbelt. His region is heavily affected by lake-effect snow and wind.
It may actually allow his truck to retain warmth enough to keep running.
I once lived out that way and we often covered the hood of our truck and kept an incandescent bulb on when the truck sat.
If we didn't prepare like that... we were not going anyplace, except maybe on foot!