IN THIS FEATURE Performance and efficiency Parallel hybrid system Different modes for different driving styles Outperforming conventional engines... The biggest challenge

On the road, the diesel-electric hybrid functions in a similar manner to the petrol-electric alternative, the energy released when the car slows being used to recharge the batteries. About town, the car can run on its electric motor and emits no emissions. At higher speeds, the diesel engine is dominant and both can work together to provide extra performance. The diesel engine can also be used to recharge the batteries.

Several modes are available to the driver. In SEV mode, the car is driven purely by its electric motor. In this guise, it can achieve a maximum speed of 40mph and has a range of around 3 miles. For safety reasons, the diesel engine will intervene if the driver presses vigorously on the throttle pedal.

Dynamic mode compromises economy in favour of performance. Both the electric and the diesel engine work simultaneously to maximise the available thrust. This is the mode for drivers in a hurry.

In stop start traffic, the car is very nearly silent

The standard option will be employed most often. In stop-start traffic, only the electric motor is used and the car is near-silent. At higher speeds or if you give the throttle a more determined prod, the HDi intervenes. Then, when the car decelerates through 40mph, it disengages, conserving fuel.