America’s Shelby Supercars (SSC) is now officially the manufacturer of the ‘World’s Fastest Production Car’ thanks to its Ultimate Aero Twin Turbo supercar. The 1183hp (882kW) speedster set a new top speed record with an average Vmax of 255.83mph (411.76km/h), 3.11mph (5.01km/h) faster than the unofficial record set by the Bugatti Veyron. In order for the achievement to be official under the Guinness World Records’ guidelines, a vehicle testing for the top speed record must race down the course, turn around, and make a second pass in the opposite direction within one hour.
The vehicle's ‘top speed’ is calculated by averaging the top speeds of each pass in order to negate any favorable road or weather conditions. On a closed stretch of highway in Washington State, the Ultimate Aero posted a top speed of 257.11mph (413.83km/h) on its first pass and 254.55mph (409.71km/h) on its return pass to set the new top speed record of 255.83mph (411.76km/h). The speeds were recorded using a series of satellites and several on board sensors, with independent firm Dewetron on hand to monitor progress.