It depends how you measure that. But by top speed it is Saleen S7 Twin-Turbo ( Top-10-list.org) with 248 mph and if measure by acceleration it is bugatti veyron http://thefastestcars.net/top-fastest-cars-in-the-world/top-10-fastest-cars-in-the-world.htm
It is the most powerful and fastest production car in the world.
Koenigsegg CCX
The Bugatti Veyron 16.4 is currently the fastest production car.
The eighth fastest production car ever is the Enzo Ferrari
The 6th fastest production car in the world is the McLaren F1 going 240 mph
The fastest production car is the 2010 Bugatti
The fastest production (as opposed to custom built or modified) car was the Bugatti Veyron (which is still the fastest accelerating & decelerating car in the world), but the current highest speed production car in the world is the SSC Ultimate Aero TT at 257mph.
the 2nd fastest car in the world is the Bugatti Veyron. The fastest is the Gumpert Apollo.
The fastest car in the world, as of 04/13 the Venom GT is the fastest "Production car" in the world at 265.7mph, sinceall of the Veyron SS re limited to 259mph.
My hotwheel car is candas fastest production car.
The Bugatti Veyron Super-Sport is the fastest "production" car in the world (temporarily).
Technically the Ferrari FXX is the fastest naturally aspirated car in the world, however the McClaren F1 is the fastest naturally aspirated production car.