Around 150 different types of plastics are used in car manufacturing and they account for between ten and 20 percent of the total weight of a car. That figure continues to rise, as increasingly sophisticated materials are making lightweight construction affordable. According to the German Association of the Plastics Converters, 100kg of plastic can replace up to 300kg of other material. Lightweight vehicles are good for the environment because they have lower emissions, but when they are difficult or impossible to recycle because of the complex mixed materials, that gain can end up being a lot less significant.