How do I get special cars?
Solution 1:
Head to the Xbox store and download all of the free GTA 5 DLC. Then once your in-game, drive to your nearest garage and you will have a whole bunch of special cars.
Solution 2:
I also have another way, of you complete a mission that gives you a car (like the space docker mission) when you get that car put it in a characters garage then (this worked for me) as another character go to the back of that characters garage and hit the right button on the d-pad and you will see a list that says special vehicles and you should see that cars name.