To unlock this achievement, simply purchase all the production cars in career mode. What is a production car you say? It's all of the standard-grade cars that range from D-U classes. These cars have no company names in their title however. To make it easy on you, simply go to the "Buy Cars" section within career mode and sort by type. Buy them all and this achievement is yours!
Note: After you purchase each vehicle, keep them in your garage. You must have all of these cars in your garage at one time to get this achievement. Purchasing then selling them back doesn't help much here.
