Audi Q7 Hybrid: First Look

Motoring Channel Staff - 15/9/2005

An engineering first in Frankfurt where Audi is premiering its first hybrid vehicle powered by an FSI direct-injection petrol engine.

The Audi Q7 hybrid concept study is equipped with a 4.2-litre FSI V8 drive unit developing 257kW (350hp) and 440 Newton metres of torque.

An electric motor that has also been integrated into the driveline adds up to an extra 200Nm of torque taking the total drive to 640Nm.

Audi's quattro permanent four-wheel drive converts all of the engine's power and torque to all four wheels for good handling dynamics, and power is directed to the wheels through a 6-speed tiptronic transmission.

The performance figures promised by the Audi Q7 hybrid give it sports car status: a mere 6.8 seconds are required to reach 100km/h from standstill. In-gear pulling power is even more electrifying, with the SUV accelerating from 80 up to 120km/h in 5th gear in 7.0 seconds flat.

These compelling figures are made even more impressive by the fact that the Q7 hybrid tips the scales at 2410kg and returns fuel consumption figures of just 12.0 litres per 100 kilometres, nearly 13 percent less than the standard-production model.

The concept study's fine all-round capabilities are underpinned by the effective blend of high-performance FSI engine and electric motor, plus, not forgetting of course, the intelligent energy management at work in the Q7 hybrid. After all, it is energy management that enables optimum use to be made of each drive unit's potential, resulting in superior performance going hand in hand with maximum efficiency.

Two hearts beating as one: When the bonnet of the Audi Q7 hybrid is first opened, there are no immediate visible signs of its hybrid nature. The 4.2-litre 8-cylinder power unit takes up the entire engine compartment, with no trace of either an electric motor or a battery.

Unlike the conventionally powered models, the auxiliary air conditioning compressor and power steering pump units in the Q7 hybrid are powered electrically to ensure their continued operability when the vehicle is driving in pure electric mode.

The V8 under the bonnet of the Q7 hybrid incorporates the same FSI direct-injection petrol technology featured in the RS 4 engine. FSI (fuel stratified injection - read: direct petrol injection) engines are more powerful and dynamic than conventional indirect-injection units whilst at the same time being a model of fuel economy. Output of 257kW (350hp) @ 6800rpm plus a peak torque of 440Nm @ 3500rpm.

Placing a further 200 Newton metres of torque and 32kW of power on tap, the electric motor is integrated into the driveline in the ideal position, between the V8 engine and the automatic transmission's torque converter. It is linked up to the FSI engine via a separating clutch that allows the vehicle to be propelled by either one of the drive units alone or by both acting in unison. In the case of the latter mode of operation, peak power rises to 289kW of power 640Nm of torque.

This solution makes the most economical use possible of the space available, meaning that it does not impinge upon the passenger compartment in any way. Like the standard-production version it is derived from, the Q7 hybrid offers up to three rows of seats and a spacious luggage compartment.

The electric motor draws its energy from a battery system housed beneath the luggage compartment floor at the rear of the vehicle. A voltage transducer that supplies power to the vehicle's electrical system can also be found here. The tyre mobility system for repairing punctures needed to be repositioned, so has been incorporated next to the battery compartment.

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 is 12.0 litres per 100km for the combined city/highway cycles. 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.