Well BOAC, in EU-OPS country each pilot has to get at least an 8 hour sleep period plus time for physiological needs, usually one hour before and one hour after said sleep (food, shower, brushing your teeth, shagging, checking into and out of the hotel, whatever). Of course the time in the crewbus can count as rest, but only if said 8 hours sleep time plus time for physiological needs is observed, if it isn't one is legally bound to extend the rest so that an eight hour sleep period can be achieved (OPS 1.1110 1.2)
But of course that is not valid in the USA, so that particular protection might not be there.