IT'S not often that supercar owners get to stretch the limits on public roads. But a recent exotic car event in Idaho saw the owner of an ultra-rare Bugatti Veyron Super Sport hit 396.5km/h.

There were only 30 Super Sports built - but the car was the only one modded to Pur Blanc guise - complete with 895kW powerplant upgrade.

Very few vehicles can hit such impressive speeds, and even fewer are stable at that velocity, but the car seems hugely settled in the attached video evidence.

It happened near Ketchum, Idaho, as part of the Sun Valley Road Rally along the state's Highway 75, and featured a wild selection of rare supercars.

Usually the public would be outraged by such insanely quick driving - but the crowd cheers as an announcer shares the 246mph top speed over a loudspeaker. Why? Because this fast-fest was all to benefit local charities.

The Veyron Pur Blanc - one of a number at the event - set a brand new Sun Valley Road Record. But it was still a smidge under 20km/h slower than its actual top speed.

The world speed record for two-seater production sportscars is still owned by US power players Hennessey. The company's savage Venom GT set the record on Valentine's Day this year at the Kennedy Space Center's five-kilometre landing runway.

While taking the record from Bugatti was satisfying for the Hennessey team, they were quick to point out that it was still accelerating heavily at the 435.31km/h recorded top speed and that they could could have blasted past that mark on an eight-mile oval.

To be fair to our friend in Sun Valley, the Venom packs a 927kW punch and weighs just over 1200kg - less than a Toyota Corolla.

Watch the full video here.

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