It really depends upon the specific car. I had occasion to be at a local dealer that sells Bugattis a couple of years ago and chatted with the Service Manager about the Veyron that was there to be serviced. He said the cost of a major service was $30K. The mechanic commented that an oil change took 5 hours because a portion of the body had to be removed to access the dry sump tanks and filters. They also noted that there was only one tire then available, specially made for the Veyron, at $2,500 a corner. From what I understand McLaren F1s are a similar story although the more pedestrian models are cheaper to service. Makes servicing the likes of Ferraris, Astons and Lamborghinis look almost cheap.