Each race event can yield up to a maximum of A-Spec points. A non-Japanese example is the Opel Speedster which is more commonly known as the Vauxhall VX , in spite of the latter only being sold in the United Kingdom. Comedian Jay Leno , an avid car collector, is listed in the game as a manufacturer; one of his custom cars, the Blastolene Special or "Tank Car", is included in the game as a prize car, available after beating missions Also, GT Auto can now install a rear wing on some cars, making it possible to adjust the car's rear downforce, which was previously only possible on racing cars or, on the first two games in the series, cars with the racing modification performed. Barriers have considerably more friction to slow down the cars in GT4 in an attempt to stop the use of "wall riding" , but there is minimal friction between cars, so the advantage obtained by running into the side of another car instead of braking is still present. Some special prize-only cars such as the Pagani Zonda LM Race Car '01 are not visible in the vehicle showrooms, and a few do not have corresponding dealerships, and thus are unmodifiable, for example, the Formula Gran Turismo Formula 1 car.