So I bought this setup on kickstarter and it will be on general sale in 2015.
These clever little cars can run in normal RC mode or 'driver assist' mode. In The latter mode the cars use light sensors to detect the shade of the track. The closer you get to the edge, the more the car steers to try and stay on!
I've tested this system at my last few events and it's brilliant. The cars do a great job and can even be used like a scalextric car.
The controllers can organise races, give lap times and you can even set the cars to drive themselves! http://youtu.be/vSY8FXTe0tM