Mercedes-Benz has taken the wraps off two new hybrid variants of the E-Class sedan at the Detroit Auto Show - the E 300 Bluetec Hybrid and the E400 Hybrid.
The German automaker claims the diesel-electric E 300 Bluetec Hybrid is the most fuel-efficient full size sedan in the world, consuming just 4.2 litres of fuel per 100km on the combined cycle. It also emits just 109g/km of carbon dioxide, making it one of the cleanest luxury cars around.
The E300 Bluetec's 150kW 2.2 litre turbodiesel four is augmented by a 20kW electric motor, while the combined torque of its hybrid powertrain is a whopping 750Nm (500Nm + 250Nm).
As a result, the E300 hybrid is no slouch. It'll run the zero to 100km/h sprint in 7.5 seconds, on its way to a top speed of 242km/h.
Electrical energy is stored in a 0.8kWh lithium ion battery, which can supply up to 19kW and drive the E 300 on electric power alone for up to a kilometre.
The E 300 Bluetec Hybrid can also cruise at speeds up to 160km/h with the combustion engine turned off and its speed maintained purely by the electric motor, a process Mercedes calls "sailing".
Other fuel-saving features include regenerative braking and an engine start-stop function, which drastically reduces fuel consumption in heavy traffic. During low speed manouevres the E 300 operates under electric power only, saving even more fuel.
The E 400 Hybrid takes the same 20kW/250Nm electric motor and puts it behind a naturally-aspirated 3.5 litre petrol V6, which produces 225kW and 370Nm.
Acceleration is slightly quicker, with the E 400 Hybrid running to 96km/h in 6.7 seconds, but top speed is lower at 209km/h. Fuel economy is also markedly worse, at 8.7 l/100km.
Crucially for both cars, few physical changes needed to be made to the passenger compartment and boot.
The lithium ion battery sits at the rear of the engine compartment and the electric motor is sandwiched between the combustion engine and the seven-speed gearbox, so the cabin and the boot are just as capacious as any non-hybrid E-class variants.
Right-hand drive variants of both models are also planned, and the diesel-electric E 300 Bluetec Hybrid could potentially find its way Down Under.
However, Mercedes-Benz Australia's Senior Manager of Corporate Communications, David McCarthy, told TMR that a solid business case has yet to be made for a locally-delivered E-Class hybrid.
Mr McCarthy did however say that as the more efficient model of the pair, the E 300 Bluetec Hybrid would be a stronger candidate for Australia than the thirstier E400 Hybrid.
The E 300 and E 400 will go on sale in Europe and America respectively, with deliveries slated to begin in the second quarter of this year. International pricing has yet to be announced, but Mercedes-Benz says the hybrids will cost only a modest premium over similarly-engined E-Class models.