Is this the world's fastest car? Swedish 'megacar' clocks nearly 274mph with five-liter V8 engine, enormous 1,322 horse power

A Swedish manufacturer has raised the speed stakes by unveiling the world's fastest car - a jaw-dropping machine capable of almost 275mph and cost £1.67 million, the Daily Mail reports.

The Koenigsegg One:1 is being described as the 'world's first megacar' and is the most powerful production car ever built.

It is powered by a 5-litre V8 engine which develops an enormous 1,322bhp - more than ten times as much as Ford Fiesta.

The car will reportedly hit a top speed of 274mph - 4mph more than the Hennessey Venom GT and 6mph more than the Bugatti Veyron Super Sport.

Incredibly, it should be able to go from 0-250mph (400kph) in just 20 seconds.

It is also likely to be a record 'braker', with the One:1 taking just ten seconds to go from this speed back to a standstill.

The car gets its unusual name from its power-to-weight ratio, with each kg having a single unit of power.

Koenigsegg gave the One:1 its global debut at this week's Geneva Motor Show with the new halo car costing £1.67 million.

However, it is too late for anyone wanting to buy the car - Koenigsegg says it has already sold all five of the models it is building.