I'm not sure how true it is, but I have heard that fast food burgers dry out quickly due to the salt content, and dry stuff just won't decompose as quickly. So

I'm not sure how true it is, but I have heard that fast food burgers dry out quickly due to the salt content, and dry stuff just won't decompose as quickly. So a quarter-pounder left under a car seat might end up looking perfectly edible (though that is not... advised.)