R* really have cocked this right up Steal a car, take it to Los Santos Customs, click on sell car, and as soon as you click sell, press start (ps3) and press x so that you select the map. Wait for about 10 seconds, collect your cash. Once you are out of the garage, steal another car, and to your surprise you will be able to sell, again and again and again, PROVIDING you hit start and selected the map quickly after you clicked sell. This works by halting the server action long enough to stop it being sent again. When you press start after clicking sell, the server action which enables the whole '24hr period before selling again' is halted and after I guess about 5 seconds the server doesn't send the message again. Essentially after you press start and hit the map, that server packet is sent and overrides the '24hr' packet. Its a really is a poor piece of coding by Rockstar. Enjoy.