If they were pissed enough to leave a brand new macbook in your car and their booze i would think chances are they were too pissed to remember what car they left it in. Otherwise they'd have been back sooner! IMO .......just read your last post... so your little friend has thieved it away in the night..... in which case he won;t be at a loss if you keep it. Although of course the correct thing would be to hand it in.