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.)
They did this on Top Gear (or Grand Tour maybe, can’t remember). Personally, cooking doneness aside, I wouldn’t want some exhaust leakage from the engine or burning oil that’s seeping from a gasket to taint the flavor of the food even if there were a guarantee of no carcinogens from it.