In order to pursue safety, in the past, the skeleton and main components of automobiles were made of traditional steel materials. Because of all available materials in the past, only steel is the strongest, so the average weight of all kinds of cars in the world is generally between 1.2 tons and 1.4 tons. But nowadays, various new materials emerge one after another, most of which are light and strong, so scientists consider whether some of them can be developed into the "bones" of new lightweight cars. In addition, some engineering plastic bumpers, engine covers, trunk covers and magnesium alloy wheels can make the body "light". At present, the developer has applied the magnesium alloy frame to some models, reducing the body weight 15.3% and 6.2% respectively. The new energy vehicles, represented by hybrid power, which will be popularized soon, will also have new lightweight "bones" not exceeding 100kg, and the weight will be reduced by 1/4. It can be said that the car "slimming" was initially successful.