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.

It’s really inefficient. A stove has all of the heat being concentrated to one spot while a car has a whole cooling system spreading out and dissipating the heat, and cars are more efficient at that than in the 70s. Having enough heat to cook with is generally bad for an engine so by design you would want it to cool before it’s that hot.

I have had a few coworkers who put their lunch containers in their engine bay so that it would heat up for lunch though, that was for a job that had us driving around to 3-7 jobs in a day.

They have been doing this since at least the 70s, when I saw it. There is nothing preventing anybody from doing it, you just want to be sure the food is wrapped in tin foil or some other heat proof metal container that keeps the bad air out.

It’s very hard to get the car inside the kitchen.

Considering the amount of cancers related to exposures to petroleum products, is this a real question asking why we don’t cook on something that runs on vaporized petroleum products and is lubricated with petroleum products?

In the 70’s fuel was cheap.

Nowadays, if I need to let the engine run for an hour, I can go to a michelin star restaurant for the same price. (OK it’s an over statement, but there is definitely cheaper and more optimal way to cook a meal on the road)

I imagine the majority of the current crop of motor vehicle owners are not quite smart enough to realize that the hood even opens to allow access to the engine bay… Nor what parts of it get hot. Or too hot. Or are safe to access, etc. And in our modern litigious society there is simply far too much that can go wrong with this to make it worthwhile for any manufacturer to include as a deliberate feature. Like, rodent infestation in engine bays is already an issue. Imagine adding (potentially forgotten and abandoned!) food to the mix.

Edit: Another wrinkle I thought of is a lack of consistent temperature control. Your engine is designed to move your car, not remain at a consistent temperature.

The utility is also rather limited when you have access to a microwave or a convenience store. Or even a convenience store with a microwave in it, as many do.

So yeah, you can do it to be clever if you like but it’s not cut out to be mainstream activity.