Yeah you have to single player ----> multiplayer glitch the cars, and then store them in your garage. They are not available for online purchase yet.
Also the special carbine is tits, and don't buy the new masks because they do not save. I would SP2MP glitch the cars before the patch releases because you're getting them for completely free. The Turismo looks wacky as fvck, I love the Alpha, and the Jester is a sweet drive.