As a money making method, it works like a charm.
However, I notice I can't modify an owned vehicle. For example I want to change a color of my X80 to a hot pink color (it's currently locked for me). I go to the LSC, change the color from LSCHax. Go back to apartment, drive another vehicle out. The change seems to be saved. But if I restart the game, I notice the color changed back.
Is there a way to permanently save the changes of an owned vehicle?