In the 1970’s and 1980’s there were several books the either had characters that did it or promoted it.
Why is there no cooking tray in my new car’s engine bay?
Is it dangerous? (It would be less physically dangerous if there was a specific spot for it.)
That’s literally how your car’s heater works. But it didn’t get that hot because the radiator dissipates most of the heat.
What you really want is to replace the water in the radiator with fry oil, and have a little basket for deep frying things in there glove box.