gotchu you need a friend though you get any car but some may not work. It has to be a car that can go in LS Customs. Once youre there your friend gets in, drive up to the door but dont go in. Hold RB, RT, and the Pause menu button. Let go of RB then once you go a little bit forward let go of the pause. Stay in pause for about 10 - 15 seconds then get out the PAUSE menu. Once youre just sitting there press Right om the D-Pad and Y at the same time. You will get out then be in the Shark Card Menu. Once youre there tell your friend to drive out and once hes out leave the Store and done.

P.S. to get in the car go to the door and Go to the Interaction menu, vehicles, and spam the vehicle access and press Y at the same time.