The complex interplay of the combustion engine, the electric motor and the battery is controlled by the hybrid manager, at the very heart of the vehicle. It receives all information about the driving and energy status and controls both drive systems to ensure the best possible performance in all driving situations. All this whilst ensuring that the battery is neither discharged too fully, nor discharged and re-charged too frequently. The hybrid manager is an extremely powerful computer which constantly has to juggle 20,000 pre-defined data parameters. A conventional engine management unit has only 6,000 data parameters to deal with.

In other respects, too, there are still a few challenges left to overcome to achieve the best possible parallel full hybrid. For a start, there is the decoupler between the combustion engine and the electric motor. Its job is both delicate and arduous. The hybrid manager shuts off the combustion engine or switches it back on – whichever is best for the vehicle. And thanks to the combustion engine – which can start and stop in an instant – and the decoupler, the driver would not notice a thing. All the driver perceives is that when the combustion engine is stopped, he can barely hear any noise from the car.

There is also the small matter of the battery, consisting of 240 cells (347 x 633 x 291 millimetres), which is located in the spare wheel well and weighs 69 kg. The battery is rated at 38 kilowatts and 288 volts. While driving, it is charged using a regenerative braking system and the maximum torque point adaptation of the combustion engine, optimised for economy. As this can heat up somewhat during charge/discharge cycles, its temperature is kept below 40 degrees Celsius using a special air cooling system. Fresh air is sucked in from the passenger compartment, so ensuring that the life expectancy of the battery is much the same as that of the whole vehicle.

In the standard vehicle, there are also other components which depend on the combustion engine, such as the vacuum pump for the power steering, the brake booster, the air-conditioning system and the oil pump for the automatic transmission. In the Cayenne Hybrid, these are replaced and/or assisted by electric motors.

Instrument panel with transmission display