This has never happened to me and I've never heard of it happening, but it MUST occur with some frequency. Apparently, a plastic grocery bag got underneath my 8 and has melted on the exhaust piping behind the cat. Now my car smells like burning plastic when I drive and my piping looks like a picasso. I'm sure the smell will stop once it all burns away, but is there anything I should do in the meantime? (like try to scrape of the burnt plastic or leave it or clean it with industrial cleaner). Any advice would be greatly appreciated!

 

I used to have that happen all the time with the low exhaust on my RX-3's. As you surmised, it will go away after a while, but you can hasten the process by removing the worst of it with a scraper or putty knife when the exhaust is cold.