I don't know which would be worse, the food picking up the flavors of sweat and overheated vinyl or the car acquiring a new flavor to mix in with the existing aromas.
I've left a lot of food in my car before (stray french fries, etc) and nothing ever got dehydrated, though it did seem to transform into something else unidentifiable. Maybe if it was left "outside" the car on the metal -- tried that and a bird flew down and grabbed it, leaving some poop in trade.