Actually, a car will eventually rust and oxidize, at least the metal parts. I don't think tires are pure rubber, either -- they're made of synthetic materials, mostly.

Given enough time, EVERYTHING will break down. It's called the Second Law of Thermodynamics.

You guys are just too impatient, that's all. Probably the best way to get rid of really bad stuff is to stick it in the cracks when one tectonic plate is overriding another. That way it'll eventually be carried right back down into the magma, recycled, and spit back up in a volcano. Of course, it will take a while....

Nature is patient. People aren't. Sometimes I wonder if we harm nature more by our impatience or by our "use" of nature. Kudzu is one example that comes to mind....