As the player's research and development team develops more advanced features for the car, they become available on the design screen. However, all the parts have an associated cost and drive up the cost of the vehicle. They also affect the test results of the car. As time progresses, the public will demand different styles of car. For example, in the energy crisis, consumers will demand more fuel efficient cars. Ultimately it can be a game of trial-and-error finding a vehicle that the public likes.