$4 million supercar 'can reach 500 kilometres an hour'

Swedish carmaker Koenigsegg claims its new Jesko supercar should be able to achieve speeds nudging 500 km/h.

While the company hasn't been able to prove it yet, if true, that would make the Koenigsegg Jesko the fastest street legal production car in the world — by a wide margin.

The current record holder is generally understood to be Koenigsegg's Agara RS, which this car is replacing. An Agara RS went 450 km/h on a Nevada Highway in 2017. (There is no agreed upon governing body or standardised test for "top speed" so record claims are always open to quibbling by other carmakers.)

The starting price for the Jesko, which Koenigsegg unveiled at the Geneva Motor Show this week, is roughly $US2.8 million ($AUD4 million).

It has a 5.0-litre turbocharged V8 engine that can produce 1,280 horsepower using regular gasoline or 1,600 using E85, which contains 85 per cent ethanol.

It also has a nine-speed transmission with seven clutches. Most automatic transmissions with clutches (most do not have them) use one or two.

The multitude of clutches — one for reverse and six for forward gears — allows the transmission to instantly shift between any two gears.

For instance, if the car is cruising in seventh gear and quick acceleration is needed, it can immediately shift down to fourth without having to step down through sixth and fifth. That saves time when accelerating. The driver can also select gears using a stick that resembles a manual transmission shifter.

The Jesko's body also incorporates several aerodynamic features, including an enormous automatically adjustable rear wing that can produce up to 1000 kgs of downward pressure at extremely high speeds. It also has four-wheel steering. The rear wheels turn as well as the front wheels for tighter turns or smoother lane changing.

The car is named for the father of Koenigsegg's founder and CEO Christian von Koenigsegg. Christian credits Jesko von Koenigsegg, now in his 80s, with supporting the company, both financially and with his business acumen, in its early years.