I've seen people go into their garage and be able to select 'Special Vehicles'. How do I do that? Do I need to unlock it by doing a certain mission? (I play on Xbox 360 btw)
it is only possible in singleplayer by going to the garage marked on the map (different for each character). NOT the garage next to their house.
when you are in there you have to wait a few seconds (about 6 seconds) until the black boxes with the info text on it go away, then you press right on the d-pad to acces the list of special cars
NOTE: you will have to download the dlc's to unlock the cars, since that is where they come from. the dlc's are free tho :)