Final work on the Mercedes-Benz AMG One hypercar is taking place ahead of the delayed 2021 launch, and the latest testing has seen prototypes hit the Nürburgring and some of the German racetrack's surrounding roads.

AMG has two prototypes at its Nürburgring development center and one of these previously broke down on its way to the racetrack. Fortunately our spy photographer was on hand and was able to snap some close-up shots of the car, including its interior.

The break down of the prototype is just one of several setbacks that has plagued development of the Formula One-powered hypercar. Recall, the car was unveiled in concept form as the Project One at the 2017 Frankfurt International Motor Show and confirmed at the time for a launch in 2019. But getting its engine suitable for road duty—certainly no easy task—is taking longer than expected, and we're sure Covid-19 disruptions haven't helped. The last we heard is that the car will be delivered to customers in 2021.

The biggest issue has been with emissions, a task made tougher by the WLTP (Worldwide Harmonized Light Vehicles Test Procedure) emissions standard that came into force in Europe in 2019. It's a stricter standard than the New European Driving Cycle (NEDC) it replaced, and to meet it AMG is thought to have needed to develop multiple exhaust gas treatment systems, among other measures. Hopefully the car's crazy sound won't be diminished.

Mercedes AMG W07 Hybrid 2016 Formula One car power unit

Mercedes AMG W07 Hybrid 2016 Formula One car power unit

In case you've forgotten, the One features the actual engine used in Mercedes' multiple championship-winning F1 cars (specifically the unit from the championship-winning 2015 car) mounted in its middle, in this case a 1.6-liter turbocharged V-6 complete with an 11,000-rpm redline and turbo-mounted electric motor-generator. Three additional electric motor-generators feature in the One, with one mounted to the engine and a further two at the front axle to form an all-wheel-drive system.

Combined output is above 1,000 hp. The particular setup also makes electric driving possible, though a range estimate isn't clear as there are no details on the size of the onboard battery.

Mercedes-Benz AMG One

Mercedes-Benz AMG One

Some performance estimates we do know include 0-60 mph acceleration in well under 3.0 seconds, 0-124 mph acceleration in under 6.0 seconds, and a top speed of around 217 mph (likely limited by the aerodynamics). Former AMG boss Tobias Moers even suggested the One could break the Nürburgring lap time of 6:11.13 set in 1983 by a Porsche 956 race car with Stefan Bellof behind the wheel, which would make it the fastest production car by a significant margin. Of course, the overall record for the 'Ring is the 5:19.55 set by Timo Bernhard in 2018 in the Porsche 919 Evo time-attack special.

Helping to develop the One is none other than F1 ace Lewis Hamilton. The seven-time world champion has even expressed an interest in developing his own specification, a potential “LH” special edition.

Lewis Hamilton with a Mercedes-Benz AMG One prototype

Lewis Hamilton with a Mercedes-Benz AMG One prototype

Beyond the special powertrain, the One benefits from high levels of downforce. The active aerodynamics, which underwent wind tunnel testing with help from F1 engineers, features a multi-part, two-stage extendable rear wing for maximum downforce in race mode. We hear as much as 1,500 pounds. You can see it in action in the video.

Also borrowed from the world of F1 is the One's push-rod suspension design and lightweight carbon-fiber construction.

Mercedes-Benz AMG One spy shots - Photo credit: S. Baldauf/SB-Medien

Mercedes-Benz AMG One spy shots - Photo credit: S. Baldauf/SB-Medien

Sadly, just 275 examples will be built and all build slots are sold. Production is expected to take place at Mercedes' F1 base in the U.K., using the same suppliers as the F1 team.

When it finally arrives, the One will go up against another hypercar loaded with F1 technology, the Aston Martin Valkyrie. The Aston was also originally due in 2019 but has also been delayed until 2021. Road-going versions of new Le Mans Hypercar contenders from Toyota, Scuderia Cameron Glickenhaus and ByKolles Racing should also provide some competition, although at this point it isn't 100% that any of these will actually be built. Ferrari is also working on a new hypercar to suceed the LaFerrari.