Hello; All car owners have faced a situation where they needed a quick solution but didn't know where to look it up. After years of working, car professionals have solved these problems and found the best solutions. We have found their best tips for you. The screw repair should be a temporarily one and might be dangerous when driving fast on german Autobahn. But for driving in city traffic it should work. On the first one: I seriously doubt that most chassis are made of plastic. At least at the moment most cars should still rather be made from steel and/or aluminum. Been to car plants before and also worked for a large car manufacturer and the chassis/body would contain some plastics but still be mostly made from tin steel that gets shaped in a huge press.