Okay, I have been told, and read, many times that to kill a car the easyest way is to drop something plastic in the tank. The plastic dissolves making a thick gel that clogs the engine. What I don’t understand is, if this works, how do the plastic canisters of gas (for lawnmowers and such) hold it without melting?
Easy… different types of plastic. Gas or jerry cans are made from High Density Polyethylene (HDPE). According to the net, HDPE is a rugged material which is easy to mould, has a high resistance to impact and is not affected by most chemicals: Working Temperature Range: -35ºC to +65ºC.
Here’s a page showing some diffent plastic types… I’m not a plastic engineer so I can’t say which type dissolves with gasoline… probly some of the lower grades or other types. Lots of pages on plastics on the web.
WAG here:
They use a kind of plastic that doesn’t dissolve easily in gas. Or they line the containers with teflon/something to stop it dissolving.
This information will, I’mm sure, prove useful for my ongoing chocolate teapot project. 
Once while trying to start a charcoal bbq w/ just a boat and a match I poured gas into a plastic disposible cup. poured some on hte coals and when I got back to the cup the remaining gas disolved it’s way through the bottom of the cup.
When I was a kid (and didn’t know better) I poured gasoline into a styrofoam cup. The cup disintegrated right before my eyes.