The fastest production, street legal super car to have been tested is the Dauer 962 Le Mans, with a time of 2.6 secs and a top speed of 404kph (just under 250 mph) The time it posted was also accomplished with street tires not slicks. This a production, street legal car that you can conceivably purchase, if you have $800,000+ in change. Being a production car simply means it came out of testing and prototype stage to be produced as road going vehicle to be sold, regaurdless of the number of vehicles produced...making the 962 a production vehicle. Vehicles such as the Hennessey Venom 800TT that claim to do 0-60 in 2.4 seconds are modified cars built by tuners with aftermarket parts, it would be no different than taking a honda putting enough nitrous and aftermarket parts in it to bosst the horse power to around 1000 and achieving sub 3 0-60 times, although it is based off a production car..realistically all that remains the same in these cars is the body design and the chasis. In essence these carse dragsters not street-legal road going cars. It all depends on what type of category of cars you are talking about. However strictly by the numbers the 962 beats the Mclaren F1 lm, Enzo, and claimed speed by Veyron (which has yet to be officially tested) If you would like more info on the specifications, history, and abilities of the Dauer 962..check out the site:

Dauer 962