This version of the One:1 has its roof removed. While it is not possible to stow the One:1's roof in the front luggage compartment as on other Koenigsegg models, it can still be removed. However, the reduced cooling thanks to the loss of the roof-mounted air intake and the increased drag mean that this is the slowest configuration of the car and is intended more for low-speed crusing than hot laps. This version is based on the petrol version, so has a reduced power output of 1160hp.

In order for the One:1's 5.0l V8 to develop the full 1360hp, it has to be running on E85 bio-ethanol fuel. However, thanks to Koenigsegg's Flex Fuel system, it can also run on petrol. This results in a reduced power output of 1160hp, with a lower redline.

Koenigsegg is creating six uniquely developed and designed production cars: the One:1 program. This is one of the most exclusive production car programs ever envisaged.

The hp to kg curb weight ratio is an astonishing 1:1. This is the dream equation previously thought impossible. On top of this, the One:1 is the first homologated production car in the world with one Megawatt of power, thereby making it the first series produced Megacar. These are the reasons for naming the car One:1.

The 2014 One:1 truly raises the bar of performance. The One:1 features new and unique solutions to enhance track performance without compromising top speed or everyday usability, with a stunning visual appearance to go with it.

Examples of features; unique track-optimized aero winglets, extended venturi tunnels and side splitters, Le-Mans inspired active wing configuration and optimized active undertrim air management. Large air vents for improved cooling, roof air scoop to support the 1 Megawatt of power, 8250 RPM rev limit, complemented with Custom made Michelin Cup Tires, upgraded rear triplex suspension with carbon bevel springs and active shock absorbers and ride height, combined with upgraded revolutionary Koenigsegg Aircore carbon fiber wheels.

Koenigsegg was the first extreme car manufacturer to take steps toward green technology with the release of the biofuel CCXR in 2007. The One:1, a sibling of the highly competitive Agera R, follows in the footsteps of the CCXR as it also runs on E85 biofuel, race fuel or normal gasoline.

In order to give the One:1 maximum flexibility when it comes to power delivery, Koenigsegg has implemented its patented variable turbo geometry technology in the One:1 program. This technology gives improved response and more low-end torque than otherwise possible. As an example the One:1 engine has over 1000 Nm of torque between 3000 to 7500 rpm, which is truly unheard of.