The space you have in your engine bay varies widely from model to model and year to year. Ideally, you want a space big enough to hold your carefully foil-wrapped parcel of food securely, so it doesn’t slide around -- but not so tightly that your food gets squished beyond recognition. Do a simple space test with a little cone of aluminum foil. Use a ruler or tape measure to make the cone 5” tall. Put the cone in the spot you intend to test in your engine bay, then drop the hood. Lift it again to see if the cone is squished, then measure the damage. This will tell you how much space you have in the area where you’re thinking of cooking.

If your intended cooking space is tall enough, but leaves a lot of sliding room for your food from side to side, wad up additional aluminum foil to bolster your packet of foil-wrapped food. Think of it like shipping something fragile. You want to make a cushion of aluminum foil around your packet of food so that it doesn’t move while you drive.