I once had a dream in which I was taking a number of bizarre, illogical classes. Psychologists would probably blame this on me worrying about my schooling as I fell asleep. Anyway, most of them were stupid, impossible, or both. But one of them strikes me as potentially useful in the real world. It was called "Engine cooking."
In it, we would take a metal mold, fill it with ingredients, stash the mold in the engine compartment of a car, and then go drive around a bunch, then afterwards, we'd retrieve the mold, open it, and note the condition of the food. In the dream, you had to produce not just edible, but good looking food too. No one wants to eat a flat suffle, after all.
This is a potentially useful idea, because engines make a lot of heat. Heat that we currently discard into the atmosphere. Cooking, meanwhile, requires a controlled application of heat. Why not feed one into the other? Especially if you're driving somewhere where you'll need food on the other end, like a party. Bake your cake....by driving there.
Well, the biggest objections would be that engines are full of things that you don't want in your food, like dirt, sludge, motor oil, and insects. Heat transfer isn't ideal without doing something crazy like running the coolant through pipes on the outmost layer of the mold, which would make removal difficult. Also, engines might be hot, but the heat is quite uneven. Food needs to be evenly heated, or you'll have one raw side and one burnt side, neither of which is edible.
So, probably not practical in the real world, where things like physics and chemistry and basic logic apply.