You know and I know that some people are not going to be able to resist the temptation to talk about parade vehicle physics and so on. So here's a thread for that.
Roughly, here's what's really going on: the physics-enabled tour vehicle is a small number of linked tiny prims. The driver sits on it, as can a small number of additional avatars. The wagon and horse are attachments *worn* by the avatar(s). So our prim limits are more about lag, than SL vehicle physics.
Also, we expect the tour route to start in L.A. (brand new server :D) where vehicles essentially will be rezzed out of a scripted rezzer that gives them their tour route ... then driver attaches it ... then others sit ... anf off you go, with a timing interval for the next float ... and the programmed route takes you through the four sims, ending in NFS.
More tech details will be posted in this thread shortly.
regards JP