Apart from the overall challenge of taming a Formula 1 drivetrain for the road, the main difficulty was exhaust gas aftertreatment, said Jochen Hermann, Mercedes-AMG technical director. "The project was partly a curse and a blessing at the same time," Hermann said. "But we have walked the stony path."
To comply with Euro 6 pollution regulations, the gas treatment system includes four metal catalytic converters, two ceramic catalytic converters and two particulate filters – and a titanium muffler.
In the end, the One has CO2 emissions of 198 grams per km – equivalent to that of a nonhybrid premium SUV -- with fuel efficiency of 8.7 liters/km, or 27 m.p.g., Mercedes says.
The One’s powertrain is based on a 1.6-liter 6-cylinder single turbocharged gasoline engine, with four overhead camshafts. Pneumatic valve springs rather than manual ones allow it to reach 11,000 rpm. The turbo is direct-driven by a 90 kilowatt electric motor.
The major advantage to this arrangement is quicker response from idle speed across the rev range, Mercedes said, and boost pressure can be maintained even when the driver takes a foot off the accelerator pedal. In addition, the electric turbocharger can act as a generator to charge the battery or feed electric motors on the front axle or connected to the engine itself.
Mercedes says the electric motor on the engine, which is connected to the crankshaft, has an output of 120 kilowatts.