European versions of the seven-seat Audi Q7 benefit from an upgrade this week courtesy of a new version of its 3.0 V6 TDI engine, bringing lower emissions, higher power and torque, plus improved performance and fuel economy.The 2008 Model Year Q7 3.0 TDI Quattro is now equipped with an exhaust-cleansing Diesel Particulate Filter (DPF) and forms part of a Q7 development program which also includes petrol/electric hybrid versions that slash fuel consumption and emissions by over 20%.
Featuring an advanced common-rail direct fuel injection system using sophisticated piezoelectric quartz crystal technology, the upgraded V6 TDI benefits from enhancements that boost combined cycle fuel economy 33.6mpg to 34.9mpg, reduce CO2 output from 279g/km to 260g/km and bring down the 0-62mph time by 0.6sec to 8.5sec. Power rises from 233hp to 240hp, delivered at 4000rpm, and torque increases from 369 lb-ft to an even healthier 406, available from just 1750rpm.
Diesel is not the only source of power to be championed by Audi. As well as exploring the possibilities opened up by second generation `future fuels' such as the biomass-to-liquid (BTL) SunFuel, Audi is also testing fully operational prototypes running on bioethanol (E85), CNG (compressed natural gas) and petrol/electric hybrid power.The Q7 hybrid is expected to go on sale in its first markets towards the end of 2008, combining its familiar 280hp 3.6 liter FSI petrol engine with an electric motor situated in the drivetrain powered by a 288-volt nickel metal hydride (NiMH) battery, which adds a further 51hp. The Q7 hybrid reduces fuel consumption, and therefore C02 output, by approximately 23% compared to the Q7 3.6 FSI we know today.
Designed in a parallel configuration in which all major assemblies are arranged in line, helping to reduce weight and energy loss, the 3.6 FSI V6 with its 277 lb-ft torque peak is boosted by up to 210 lb-ft by the electric motor. Channelled via a six-speed Tiptronic gearbox through the quattro four-wheel-drive system with asymmetric 40% front, 60% rear torque split, this joint output enables a 0-62mph acceleration of just 7.6sec (standard Q7 3.6 FSI is 8.5sec) and combined fuel consumption of 28.8mpg (standard Q7 3.6 FSI 22.2mpg).
Fundamentally, three driving modes are possible. The FSI engine and the electric motor can each work on their own as the drive unit, or the vehicle can combine the power of the two for acceleration. In this mode, the petrol engine is responsible for basic operation, whereby it also needs to supply energy to the battery.
The electric motor on the other hand can operate independently and almost inaudibly at speeds of up to 30mph, reducing exhaust and noise emissions in built up areas. It is also able to feed kinetic energy back into the system and recharge the battery when the vehicle is braked or coasting. During this operation, known as recuperation, the motor reverses its function to become an alternator.The capacity of the NiMH battery allows the vehicle to be driven up to 1.2 miles on purely electrical power - coasting and braking feed additional energy into the system. When the capacity of the battery has been reached, the combustion engine is activated to recharge the battery. Through regeneration measures such as these, the Audi Q7 hybrid recuperates about 720 kWh of energy a year - approximately one-sixth of what a four-person household uses - based on an average of 12,000 miles per annum.
If the Audi Q7 hybrid is coasting without the accelerator pedal being depressed, the combustion engine is switched off - this is possible at speeds up to 74mph. It is also switched off if the vehicle remains stationary for more than 3sec. To continue the journey, all the driver has to do is to remove his foot from the brake and depress the accelerator again.
Like the standard Q7, the hybrid also has space for three rows of seats and a large luggage compartment. The battery system that powers the electric motor is located in the spare wheel recess. Compared to earlier generations of hybrid vehicles, the electric motor and battery are extremely lightweight. The battery weighs 152 lb and the hybrid module with the electric motor 88 lb.