The Corvette C3 was the third Corvette model. It was made from 1968 to 1982. The C3 was very similar to the C2. The main changes were the body and the inside. The V8 engines from the C2 became more powerful. In 1971, because the engines were too bad for the environment, the engines' power went down. This made the C3 slightly slower and less powerful. Every year the engines became less powerful until 1975. This was because the U.S. government forced GM (General Motors) to make the engines better for the environment. The C3 Corvette convertible was not made after 1975, so only the coupe was for sale after 1975.