There's something going on funny across the borders of the racing sims - there's this big land-wall going across the racings sims, especially the track.
The thing is, it only shows up when you're right *at* the sim border, you can't see the wall from farther away. (And it prevents vehicles from crossing)
eg. At Brilliant (1, 205) you can see what I'm talking about. The same goes for the other borders of the racing sims.
It's really screwing up the racing track for vehicles.