Porsche just broke the production car record at the Nurburgring in their new 918 Spyder with Porsche test Marc Lieb at the wheel. The car was fitted with Michilin Pilot Sport Cup 2 tires to break the record. And yes technically the Radical and others can be driven on the street(in Europe, not the US) and hold faster lap times but they really aren’t production cars in the proper sense of the word.
http://www.youtube.com/watch?v=bEv_uFBnzwI
