and the 2012 race was awesome if only because of the sheer number of electric vehicles on the track at one time. The electric car portion in 2012 had over 30 entrants, 12+ of which were either Tesla Roadsters or Tesla Model S's. It was simply amazing watching an electric car race where there was a serious traffic jam problem because of the number of cars on the track at the same time.
I believe it was Brian Hall (a long time electric race vehicle builder) who said to me, watching this spectacle, that it was almost certainly the largest number ever of high performance electric vehicles racing on a track at the same time.
For the 2013 event, signups are now open. It costs a bit of money to participate, and the amount is a fraction of what it would cost for a regular track day. The total number of entrants per class is being limited.
The company is encouraging anybody with an electric car to enter, and the 2011 and 2012 events had a number of Nissan Leaf owners participating.