Take note of these numbers: 1,341 hp to 1,360 kg. It's a ratio that gives the latest hypercar from Sweden's Koenigsegg the potential to be the fastest car on Earth, with a listed 273-mph (440 km/h) top speed. It also gives the car its name: One:1. That's one horse for every kilo, or close enough to round up without thinking twice. Starting with the already ultra powerful, lightweight Agera, Koenigsegg reached deep into its bag of tricks to strip more weight, add more downforce and create one of the world's most extreme machines.

The One:1 is a sort of 20th birthday celebration for Koenigsegg. Back in 1994, when Swedish sensation Ace of Base was taking the world by storm, a bright eyed 22-year-old named Christian von Koenigsegg decided to follow a dream that would eventually make him a Swedish sensation in his own right. He set out to start a car company and design an exotic sports car. It's a dream that many a child has had, but not many adults have pursued. Koenigsegg drew from his well of passion and "mind-bending will" to go beyond just seeing it through, growing and evolving the dream for the next two decades – from the original CC8S, to the once-world-fastest CCR, to the One:1, with a few others in between.

Evolution skips ahead a few steps in the One:1. Koenigsegg explains that this riveting piece of engineering not only boasts the 1 hp/1 kg ratio, it is also the world's first homologated production car with a full megawatt of power. That leads Koenigsegg to coin what very well may be the next evolution of sports car nomenclature. Beyond the "super" and "hyper" cars lies the megacar.

The extra power pushing the car into mega territory comes from a variety of modifications to the 5.0-liter twin-turbo V8, including a strengthened block, new head gaskets and variable geometry turbocharging. The upgraded engine cranks out more than 738 lb-ft (1,000 Nm) of torque between 3,000 and 7,500 rpm, with the max torque of 1,011 lb-ft (1,371 Nm) coming at 6,000 rpm.

As impressive as the power and torque figures are, they're really only the introduction to a much longer story. Each year, supercar manufacturers find ways of adding more and more horsepower to their grumbling, four-wheeled beasts, but Koenigsegg undertook a much more careful balancing act. In addition to adding more than 200 horses above and beyond the Agera R, Koenigsegg indulged a weight-savings obsession, carving, slicing, molding and shaving materials and weight in every way it could think of.

"We had to fight really, really hard to reach that goal [of a 1:1 ratio]," Christian von Koenigsegg explained at the Geneva Motor Show press conference. "It's about 80 kilos lighter than our normal [Agera]. We had to change the carbon fiber type to a newer, later grade, which is used in Formula 1 today, re-engineer all the layup schemes in the body and the monocoque. We have put more titanium. We have lightened everything we can find – thinner glass area, thinner, lighter seats with memory foam ... just really optimizing everything."

That weight saving arrives in spite of the fact that the One:1 gains 66 lb (30 kg) in new features like active aerodynamics and suspension systems.

The One:1 loses some of the smooth, rounded looks of the Agera R because it has a fully revamped aerodynamics package. The face of this package is the massive splitter and side winglets up front, which add downforce, an effort aided by the new hood outlets and active flaps below the splitter. According to Koenigsegg, the massive wing jutting off the rear slope of the cabin is the world's first top-mounted, active rear wing.

"The reason why it's top-mounted is because the underside of the wing is the most important for aerodynamics to create downforce," Christian von Koenigsegg explains. "It's the equivalent of the top side of an aeroplane wing."

The wing is electronically controlled and hydraulically activated, adjusting between high downforce and low drag based upon vehicle speed and G-force. The One:1 has 1,830 lb (830 kg) of downforce at its top speed of 273 mph (440 km/h) and 1,345 lb (610 kg) at 162 mph (260 km/h). The wing can also assist in extreme braking, helping the One:1 halt from 249 mph (400 km/h) in 10 seconds flat.

Koenigsegg promises that, despite the fact the One:1 has a simulated top speed a few mph's higher than the latest world's fastest car – the Hennessey Venom GT – the One:1 is designed to be every bit as thrilling around the corners and S-curves of the track as on straight runways. In fact, it goes so far as to say that top speed wasn't a priority in its development ... but it is equipped with tires rated to 273 mph (440 km/h), just in case the driver feels the urge. The One:1 can spit out 2 Gs of cornering force and has an active suspension system to adapt to the driving conditions at hand.

Zero-to-62 mph times appear a little passé for a car of the One:1's caliber. Koenigsegg only lists the not-so-practical 0-249 mph (400 km/h) time of 20 seconds. With that type of quickness, the One:1 may just follow in the footsteps of the Agera R, setting acceleration records in place of top speed records.

The One:1 has a carbon-Kevlar body fixed atop its honeycomb-core carbon fiber monocoque. The combination is 20 percent lighter than the Agera thanks to the use of M46J and M55J carbon fibers. The model loses Koenigsegg's traditional hood-stowable roof for a fixed panel due to the aerodynamic modifications to the hood.

Inside, the driver and passenger are secured to their lightweight racing seats with six-point harnesses. Koenigsegg loves talking about the memory-foam aspect of the seats, which dials in personalized fit and comfort. A 3G telemetry system connects with the owner's iPhone and also provides lap times and other performance features.

Koenigsegg only plans to build six examples of the One:1, and every one of them is already spoken for. It didn't share how much those buyers are spending on the purchase, but we're quite sure the price is comfortably into seven-figure territory.

Source: Koenigsegg