These shuttles are very hit and miss. Taking your own car down to Mulsanne is much less hassle on PQ weekend than during the race. One year we decided to shuttle off to Mulsanne during the race at about 10 in the evening and the one driver, who had been going back and forth all day for 10 hours without a replacement, just downed tools and the whole thing ground to a halt. Also, once nearly got stuck out at Mulsanne 'cos there were about 300 people queueing for the last bus. Only a 6'6" tall 18 stone mate saved the day or we'd have spent the night (have done that too - good bivvie spots on the banking - earplugs for those who don't find the sound of those Vettes as good as a lulabye for putting you to sleep.)