faster cars like the pagani zonda are made from carbon fiber since it is light weight and strong
street cars like what you see around are made from fiberglass light but not as strong as carbon fiber in my opinion
and then there are classics that are made from steel heavy but stronger than carbon fiber and fiberglass
i hope this helped you better than the last persons answer
ckinweaver my answer: first they use aluminum they send the aluminum body to Japan and they improove the body and they put minerals & other crud to enhance the metal. This is used in normal Toyota ford Subaru and the leading legal street car industries