Mercedes-Benz has announced what it says is the world's most fuel-efficient luxury car, one of two E-Class hybrids that will make their world debut at the Detroit motor show, on from January 14-22.
The E300 BlueTec diesel-electric hybrid (available in Europe in sedan and estate format from late 2012) is rated at an impressive 4.2 litres per 100km.
In real terms, that equates to a 15 percent improvement on the current E250 CDI, with performance equivalent to that of the E300 CDI.
So, how does it work? By combining a two-litre, four-cylinder turbodiesel producing 150kW and 500Nm with a 20kW/250Nm electric motor, as well as engine stop/start, regenerative braking and a short-range battery-only capability, that's how.
And, by tucking the lithium-ion battery away under the rear seat, there are no compromises on the boot volume or rear-seat comfort, and no changes to the body shell.
The system is also modular, so it will be possible to develop hybrid variants of other models relatively quickly and cheaply.
A case in point is the E400 hybrid, which will also premiere at Detroit; it teams up a 225kW/370Nm, V6 petrol engine with the same 20kW/250Nm electric motor and battery pack, plus engine stop/start, regenerative braking and battery-only capability.
The result is a muscular luxury sedan for the North American market (followed by other countries such as Japan and China later) that rates at 27mpg (8.76 litres per 100km) on the US combined measurement.