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.)
It’s too hard to get direct contact with the engine. And thanks to the invention of plastic engine covers all the heat is trapped largely under them. We heated some burritos once on a trim on my moms grand Cherokee.
Also I have a boxer engine so it’s kinda hard to get down to the engine itself, and the plastic air intake doesn’t get very hot.