The Mercedes-AMG One can justifiably claim to be the pinnacle of roadgoing combustion engine technology. However, the car’s cutting-edge powertrain can trace its origins back over a decade.
In 2012 engineers at what is now Mercedes AMG High Performance Powertrains in Brixworth, UK, were deep into the development of an engine, or to put it more precisely, a power unit, that would dominate Formula 1’s soon-to-arrive hybrid era.
The challenge facing engineering director Andy Cowell’s team was very different to that which they were used to. This was the era of 2.4-liter, naturally aspirated, port-injection V8s in F1 that revved to the stratosphere. (Before cost control measures in 2007 put an end to such excesses, Cosworth successfully ran its CA V8 to over 20,000rpm). But F1 was about to undergo a seismic shift.
In 2014, V8s would be consigned to history, replaced by 1,600cc, turbocharged, direct-injection V6s featuring energy recovery from both kinetic and exhaust gas-driven electric machines. Even more significantly, the rules would place a hard ceiling on fuel usage, with a fuel flow limit of 100kg/h and a maximum fuel load per race of 100kg. Combustion and overall powertrain efficiency would be king, and the team that managed to coax the greatest propulsive effort from every drop of fuel would hold an advantage.
The result were engines from Mercedes, Ferrari, Renault and later Honda, that pushed efficiency to levels previously thought impossible. In that first year, Mercedes admitted that its ICE was over 40% TE, and by 2017, overall efficiency (taking into account energy recovery), was over 50%.
Mercedes committed early to development of its V6 engine. Single cylinder mules were already running in 2011, despite a late rule change from an I4 global race engine concept to a V6, on the insistence of Ferrari. This early work paid dividends and the Mercedes PU106A, fitted to the F1 WO4 car, dominated that first and subsequent seasons, both in terms of sheer performance and reliability.
The layout of the PU106A was unique, the compact V6 ICE featured a motor generator unit nestled in the vee of the cylinders, driven by a turbocharger with its compressor mounted at the front of the block and turbine at the rear. Running at up to 120,000rpm, just this one element of the engine, replete as it was with a single, spindly shaft linking all of the rotating parts, dove headfirst into the engineering unknown. The layout was a masterstroke, not least because it allowed for the use of a larger, and more efficient compressor compared to other manufacturers’ solutions that packaged both at the rear.
Of course, there were many more facets to Mercedes’s success beyond the MGU-H. Its unrivalled research into combustion science, working in conjunction with Daimler’s engineers in Stuttgart; an exceptional level of integration between power unit and chassis; pushing the limits of electric motor and battery technology (the 120kW MGU-K weighed a mere 7kg) … all these elements and more combined to deliver an unbeaten run in the F1 constructors’ championship from 2014-21.
Now this engine, albeit in a detuned form (574bhp vs F1’s 850bhp+) is available on the road. Mercedes admits that getting it there has been as tough a challenge as developing the original race unit. In part thanks to emissions hurdles related to the high NOx levels inherent with such a lean combustion engine, not to mention having to tame a highly strung racing unit to deliver acceptable service intervals and start at the push of a button – without needing supervision by a garage full of engineers.
While other cars can lay claim to having racing ‘derived’ engines, the Mercedes-AMG One stands alone in being a full (albeit limited) production road car with a legitimate F1 powertrain. For this reason, and the fact it is probably the most efficient ICE car ever produced, Mercedes should be applauded.