Audi showed a hybrid-powered version of its new Q7 large SUV at the Frankfurt Motor Show.
The Q7 concept study combines a 4.2-litre V8 FSI petrol engine with electric power, and could become a production reality by 2008.
The V8 with FSI direct petrol injection delivers 350bhp at 6800rpm and 440Nm of peak torque at 3500rpm.
A NiMH (nickel-metal hydride) battery beneath the luggage compartment, and an electric motor between the engine and Six-speed automatic transmission add just 140kg to the Q7's weight.
The electric motor can work alone up to 18mph, reducing noise and emissions in dense traffic, or can join forces with the combustion engine, adding up to 44bhp and 200Nm of torque to total output, and a 13 per cent improvement in fuel economy. The hybrid accelerates to 100km/h in 6.8 seconds, and achieves 23.5mpg.
The hybrid Q7 was a closely guarded Audi secret. It says public reaction will be a key factor in determining the Q7 hybrid's future, but says the show car is production-ready and could become a part of the Audi range by 2008.
Audi says the hybrid Q7 remains firmly planted in reality where performance is concerned. Fifth gear overtaking increment between 80km/h and 120km/h takes exactly seven seconds.
A separating clutch links the FSI engine and the electric motor, and enables the two power sources to operate individually or in unison, meaning that at any one time the Q7 hybrid can be propelled by the combustion engine or electric motor alone, or a combination of the two.
The electric motor can operate alone - in virtual silence. While doing so, it can also feed the extra kinetic energy produced during braking and engine overrunning back into the system to recharge the battery. During this recuperation phase the unit switches its function imperceptibly and in a fraction of a second to act as a generator. When battery capacity drops to a minimum, the combustion engine also cuts in seamlessly to recharge it.
If the accelerator pedal is fully depressed, the electric and V8 power are combined and the increased output cuts 0-6 seconds off the 0-100km/h sprint and two seconds of the 80-120km/h acceleration time.
If the new Q7 hybrid is stationary for more than three seconds, or is coasting without the accelerator pedal depressed, the petrol engine is automatically switched off to conserve fuel. Releasing the foot brake and depressing the accelerator restarts it. The electric motor assumes the role of the starter-alternator unit, resulting in a quiet, smooth and extra-quick starting.
The concept study also harnesses the power of the sun. Solar cells integrated into the open sky system - the Q7's large-format glass sunroof - allow the ventilation and air conditioning systems to be operated when the vehicle is parked and switched off.
The driver can also then activate the systems remotely a few minutes before starting a journey so that the cabin environment is pleasantly chilled right from the word go. Part of the battery capacity of the hybrid drive system is used to achieve this.