An intricate system of control electronics is required to coordinate operation of the two power units to optimum effect. In doing this, the control electronics naturally take the driver's commands into consideration, as communicated to the system with the accelerator and brake pedals and with the tiptronic selector lever, as well as the current road speed. However, the battery's charge status and the pulses transmitted by the ESP electronic stabilisation program are also vital parameters.
The electronics automatically regulate the interaction between the drive components and convert the driver's commands into a perfect synthesis of sportiness and efficiency. The occupants can follow what's happening in one of the sub-menus in the MMI Multi Media Interface display.
There are basically three different operating states: either the vehicle is driven by the combustion engine or electric motor alone, or the two power sources unite together to accelerate the vehicle. The petrol engine is responsible for basic vehicle operation, although it also energises the battery at the same time.
The electric motor, meanwhile, is capable of propelling the vehicle at speeds of up to 30 km/h, autonomously and in virtual silence, which comes in particularly handy when driving in city traffic. The result is a sharp cut in both harmful emissions and noise levels in built-up areas.
The battery's charge capacity allows for a range of up to two kilometres in pure electric mode, with the extra energy produced during braking and engine overrunning being fed back into the system. Once the battery's capacity has dropped to minimum, the combustion engine cuts in imperceptibly to recharge it.
The V8 FSI engine is able to unleash 350 bhp and 440 Newton-metres of torque. This power alone is enough to accelerate the standard-production Q7 from 0 - 100 km/h in 7.4 seconds. If the driver is looking for even snappier response, the electronics engage the electric motor too. Unlike combustion engines, the motor's additional thrust, with up to 200 Nm of torque, is available instantly when the vehicle pulls away.
Out on the road, this takes acceleration into a new dimension, particularly so at low speeds. Just four metres after starting from standstill, the Q7 hybrid is already a metre ahead of its V8 petrol-engined sibling, with the electric motor's boost effect shaving a whole 0.6 seconds off the time for the 0 - 100 km/h sprint. The auxiliary drive unit has an impressive effect on pulling power too. The vehicle accelerates from 80 up to 120 km/h, the typical step-up in speed when overtaking, a good two seconds or around 25 percent quicker. Drive power is boosted automatically the instant the driver depresses the accelerator pedal fully, with the necessary electrical energy drawn from the rear-mounted battery.
The electric motor is capable of far more than just providing auxiliary power though, as it also regenerates the kinetic energy produced by braking or driving downhill in overrun mode and feeds it back into the system to recharge the battery.
During this "recuperation" phase, the unit switches its function in a fraction of a second to act as a generator, without the driver noticing the slightest change.
An additional function for streamlining the new drive system's efficiency is just as imperceptible to the driver. If the vehicle is coasting without the accelerator pedal depressed, the combustion engine is switched off. The same fuel-saving measure is initiated whenever the vehicle is stationary for over three seconds. All the driver has to do to resume the journey is release the brake pedal and depress the accelerator and the petrol engine will immediately spring back into action.
The electric motor assumes the role of the starter-alternator unit, resulting in a quiet, smooth and extra-quick starting process.
Thanks to these strategies deployed by its intelligent energy management, the drive system boasts a high degree of efficiency. Despite its far superior acceleration, an identical top speed and the increase in vehicle weight, the Q7 hybrid burns around 13 percent less fuel than a comparable standard-production model fitted with a combustion engine only. Average fuel consumption in the MVEG cycle is 12.0 litres per 100 km. When driving purely in city traffic, where frequent energy recuperation makes even greater reductions possible, the hybrid vehicle's fuel-saving potential can be harnessed to yet greater effect.
The concept study uses sunlight as yet another source of energy: the Audi development team has integrated solar cells into the open sky system – the SUV's large-format glass sunroof – which allow the ventilation and air conditioning systems to be operated when the vehicle is parked. This represents a valuable boost to comfort, particularly on hot summer days when the driver is also able – for the first time – to activate the climate control system remotely a few minutes before starting the journey, so that passengers find a pleasantly cool interior awaiting them. Part of the battery capacity of the hybrid drive system is used in order to achieve this.
The visionary systems onboard the Audi Q7 hybrid concept study once again provide an impressive demonstration of the "Vorsprung durch Technik" philosophy that the company is so renowned for. It is a technological pioneer that showcases solutions to not just one but several of the most pressing challenges facing tomorrow's automotive society, fusing as it does so motoring pleasure with rationality, supreme comfort and maximum efficiency.
The equipment, data and prices stated here refer to the model range offered for sale in Germany. Subject to amendment; errors and omissions excepted.