As revealed to CarAdvice at the Mercedes-Benz S-Class international launch in July, the S500 Plug-in Hybrid combines an electric motor with the 245kW/480Nm 3.0-litre twin-turbocharged V6 petrol engine already utilised in the S400 overseas (and, in Australia currently, the E400).
Mercedes-Benz has, however, now confirmed that the electric motor produces 80kW of power and 340Nm of torque. Although the brand won't provide combined outputs for the petrol engine/electric motor combination, it is claimed the Plug-in Hybrid version of the Mercedes-Benz S-Class will achieve a 5.5 second 0-100km/h and on the combined fuel consumption cycle achieve 3.0L/100km, with corresponding CO2 emissions of 69g/km.
Also available is a Hybrid mode, where the S500 may not be readily charged via an external power source and therefore the petrol engine and electric motor work together, with the engine and regenerative braking system charging the batteries to power the electric motor; E-Save, which is a driver-selectable mode that allows a fully charged battery to be 'saved' to be used later in, for example, an urban environment rather than freeway driving; and Charge, where the battery is charged more determinedly while driving.
As revealed earlier, a charge point is located on the lower right side of the S500 Plug-in Hybrid, permitting owners to connect to any standard household power socket and recharge the 8.7kWh battery, which is stored behind the rear-seat backrest (with an accompanying, and as-yet undisclosed boot volume reduction).
The S500 Plug-in Hybrid also features what Mercedes-Benz call an 'anticipatory energy management system'. It uses navigation data and the internet - Benz's Comand online - to adjust the priorities of the hybrid's recharging process and use of the petrol engine or electric motor, depending on what terrain is approaching and the current driving style.
The German manufacturer claims the S500 Plug-in Hybrid can, therefore, use more of the battery energy content on an uphill stretch of road instead of relying on the petrol engine, for example, if the navigation system indicates a downhill stretch will follow soon after that will help recharge the batteries.
Mercedes-Benz says the S500 Plug-in Hybrid is the first model to incorporate a second generation recuperative braking system to help more efficiently charge the battery cells. While the brake pedal is claimed to have improved in response, to feel more natural, at the same time a braking sensor can more accurately divide a portion of the brake pressure dictated by the driver between actually braking the car and providing recuperation.
As with non-plug-in Mercedes-Benz hybrid models, a clutch pack sits behind the internal combustion engine to disconnect the engine from the electric motor, which is located just ahead of the seven-speed automatic transmission. The S500 Plug-in Hybrid also enables the petrol engine to switch off when the driver is off the throttle and coasting, using the deceleration torque to also recharge the batteries.
Unlike with the Mercedes-Benz S400 Hybrid (non plug-in) available in the US - but won't be available in Australia - which teams a 3.5-litre non-turbo V6 with an electric motor, Mercedes-Benz previously told CarAdvice that engineers could achieve similar economy figures with drastically improved performance by using a 3.0-litre twin-turbo V6 petrol engine.
Mercedes-Benz Australia says it is interested in bringing the S500 Plug-in Hybrid to market, but no decision has yet been made.