Sitting between the current ’43’ and ’63’ AMG models, the new ‘53’ hybrid-engine Mercedes features a turbocharged, hybridised inline-six cylinder engine.

Mercedes-AMG has announced a new 335kW twin-turbocharged straight-six, petrol-hybrid engine that will be installed in the company’s new CLS coupe-saloon and E-class coupe and cabriolet models.

Confirmed at the Detroit Motor Show, the new 320kW petrol engine features the company’s EQ Boost starter-alternator (a combined starter motor and alternator) in an electric motor that’s installed between the straight-six petrol engine and an AMG Speedshift TCT 9G transmission.  The electric motor generates the additional 15kW and 250Nm of torque, the latter combining with the internal combustion engine’s 520Nm.

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The 3-litre in-line six is equipped with two-turbochargers – a conventional exhaust gas turbine and an electric turbocharger. The latter not only charges the electric motor through the car’s 48 volt electrical system but also provides near instantaneous maximum torque from idle to eliminate any lag until the larger exhaust driven turbo is up to speed.

When installed in the new 1980kg CLS, the 53 engine results in a 4.5-second 0-100km/h time and a 270km/h maximum if the optional AMG Driver’s pack is ordered (it’s a plain 250km/h if not). In the new E 53 coupe and cabriolet the numbers are 4.4 and 4.5-seconds respectively with the same top speed options. At the introduction of the 53 engine Mercedes confirmed there will be no CLS 63 or E 63 coupe or cabriolet model.

Mercedes’ EQ Boost technology is pivotal to the car’s 48 volt electric system, not only taking on the role of the car’s alternator but is also key to the model’s hybrid functionality, such as the engine’s idle speed control, a first for Mercedes. Along with the 15kW and 250Nm of torque produced by the electric motor, the hybrid function of the car also takes care of energy recuperation, gliding mode and the engine’s stop/start system which, Mercedes claims, is virtually imperceptible in operation.