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Saturday, January 26, 2008

Audi Q7 In Depth


The engines of the new Audi Q7 ensure a level of performance promised by the vehicle抯 outward appearance. Torques of 440 and 500 Newton-metres deliver tractive power in all speed ranges to masterfully fulfil every driver抯 wish.

Two power plants are available for the debut of the new SUV with the four-ring badge: a new 4.2 litre V8 with FSI direct petrol injection and the powerful yet quiet 3.0 TDI with common rail system using piezo inline injectors. Other engines will be added to the range.

The V8 is a close relative of the equally large power plant that drives the currently most dynamic Audi, the RS 4. The engine belongs to the present V engine family of the brand, notable for a 90� cylinder angle and a distance of 90 millimetres between cylinders. An additional distinguishing feature: the four camshafts are activated by a two-stage chain drive system at the rear of the engine.

Like the RS 4 engine, the V8 in the Q7 has FSI direct petrol injection, which � following five victories in the Audi R8 Le Mans racing car � is now being introduced in a production eight-cylinder model.

FSI engines deliver more power and dynamism than the conventional power plant with manifold injection � and they do so with outstanding fuel economy. With this remarkable achievement, Audi is opening up a new dimension in the efficiency of standard petrol engines, demonstrating once again the brand抯 proverbial 揤orsprung durch Technik�.

The V8 has been retuned for use in the Audi Q7. A fuller torque curve up to nominal speed and spontaneous response � these are the characteristics of this new engine.

The engine excels not only with its dominant power output (257 kW/350 bhp) at 6,800 rpm and a maximum torque of 440 Nm at 3,500 rpm. The resultant driving performance is excellent, even in the face of tough competition.

In just 7.4 seconds the new Audi Q7 4.2 quattro sprints from zero to 100 km/h and accelerates superbly up to a top speed of 248 km/h. Fuel consumption: only 13.8 litres of premium plus fuel per 100 kilometres (overall / provisional figure).

With piezo injectors: 3.0 TDI

Another power pack is being introduced in the Audi Q7 in the form of the six-cylinder 3.0 TDI. Compared with competitor models, this engine offers more than impressive power and torque potential: 233 bhp and 500 Newton-metres. Maximum torque is available just above idle speed, from 1,400 rpm � giving the driver powerful acceleration in all speed ranges.

Despite having a torque-converter transmission, this delivers a driving performance that is hard to find elsewhere among SUVs with V6 engines: the speedometer needle passes the 100 km/h mark a mere 9.1 seconds after driving off; the Audi Q7 3.0 TDI quattro goes on to reach a top speed of 216 kilometres per hour.

Fuel consumption: the 3.0 TDI requires no more than 10.4 litres of diesel (provisional figure) on average per 100 kilometres. This equates to a range of almost 1,000 kilometres. At the same time, exemplary noise quality and compliance with the strict EU4 emissions standards are truly convincing achievements. The Q7 3.0 TDI quattro is fitted as standard with a diesel particulate filter.

The V6 four-valve engine with turbocharger technology and map-controlled, cooled exhaust gas recirculation also belongs to Audi抯 new family of V engines and features a chain drive for camshafts and oil pump.

Mixture preparation is performed by a latest-generation common rail system. It has a high-pressure pump and an injection rail for each cylinder bank, increasing maximum injection pressure to 1,600 bar. The high injection pressure ensures even finer atomisation of the fuel and therefore better mixture preparation and more efficient combustion.

The piezo injectors are undoubtedly the most important innovation of the present common rail system. The injection process utilises the piezo effect: an electric voltage is applied to ceramic, altering its crystal structures. The minimal expansion resulting from this � supported by a hydraulic element � mechanically triggers the opening of the injector needle.

With piezo injectors, the number of injection processes per cycle can be varied almost at will. The Audi TDI development engineers have opted for up to five injection processes for the 3.0 V6: in addition to the main injection process, double pilot injection takes places in the lower speed range and single pilot injection takes places in the medium range. In addition to this, simple post-injection takes place up to around 2,500 rpm and under partial load.

This strategy ensures both a reduction in emissions and a smoother combustion process � which primarily benefits the engine抯 acoustic behaviour. In this area the 3.0 TDI engine undeniably sets the benchmark in its class.

Both engines are combined as standard with a 6-speed tiptronic. This transmission allows the engines� power potential to be converted into a masterly synthesis of dynamism and operating convenience.

New quattro generation

A typical feature of all high-performance Audi vehicles is quattro permanent four-wheel drive � a drive principle that is now celebrating 25 years of success in motor sport and standard production. More than two million Audi quattro models have left the assembly line so far � a number that speaks for itself.

quattro ensures excellent traction and lateral stability and minimises the effect of propulsive power on the vehicle抯 self-steering properties. This is the prerequisite for high cornering speeds and a high degree of driving stability � on and off-road.

A Torsen differential in the new Audi Q7 � with its longitudinally installed engines � automatically ensures optimum power distribution to all four wheels. The name Torsen is a combination of the terms 搕orque� and 搒ensing�. The Torsen differential is a self-locking worm gear.

Like the RS 4 most recently, the Q7 is equipped with the latest-generation quattro drive technology. Here the torque split between front and rear axle is 40 : 60. This provides the basis for even more agility � most notably when steering into bends � with practically no perceivable torque steer.

Together with direct servotronic steering � standard in all Q7s � this means that the driver enjoys a level of steering precision and clearly defined handling that up to now has been unimaginable in an SUV and which has only rarely been experienced in a sports car.


The dynamic suspension of the Audi Q7 uses proven sports technology with double wishbones at the front and rear as well as standard steel springs and twin-tube shock absorbers. Long spring travel, a ground clearance of 205 millimetres and robust components take into account the application spectrum of off-road driving. All this results in a driving performance that bears any comparison in respect of dynamism and which sets the standard with regard to ease of control, even on rough terrain.

The double wishbones at the front axle are made of aluminium, a clear advantage in terms of reducing unsprung masses: ride comfort and driving dynamics are thus enhanced. The lower wishbone and anti-roll bar are attached to a subframe of high-strength steel, on which the steering is mounted.

All Q7 models are equipped as standard with speed-dependent servotronic steering. This helps the driver to manoeuvre in or out of a parking space with minimum steering effort, and its directness and precision ensure good road contact and clear feedback at high speeds.

At the rear axle, the upper wishbone and the spring strut cross bar are made of forged aluminium. The tie bar on the other hand is made of weight-optimised tailored rolled blanks, which thanks to steel plates of varying thicknesses combine low weight with high rigidity for sections under particular loads and strain. All control arms are attached to a subframe which also supports the final drive. The tilted position of the spring and shock absorber unit reduces overall height and creates more room in the vehicle interior.

The use of rubber-bonded metal mounts with low torsional rigidity at the front and rear axle means that occupants can enjoy exceptional ride comfort.

The Audi Q7 is fitted with 18-inch aluminium wheels as standard, with 235/60 tyres (eight-cylinder: 255/55). As an alternative, other wheels (sizes 18, 19 and 20-inch) can be ordered on request. An optical highlight is unquestionably the new 20-inch 5-arm double-spoke cast aluminium wheel with the bicolor design. If the Q7 is configured as a 5-seater with 18-inch wheels, a full-size spare wheel is available.

Option: adaptive air suspension

The latest-generation adaptive air suspension is available as an option on the Audi Q7. The combination of air suspension and an electronically controlled damping system produces the perfect synthesis of truly sporty handling and supreme ride comfort. An important feature for an automobile with off-road capability: ground clearance is variable between the minimum dynamic level of 165 mm and a maximum of 240 mm (lift mode).

For normal driving, a choice of three different characteristics can be selected via the central multimedia interface (MMI) control panel, ranging from very sporty to comfortable, namely dynamic, automatic and comfort. The system control unit varies the spring and damping characteristics according to the mode selected and vehicle speed.

In parallel with this, the trim is lowered by up to 35 millimetres (dynamic mode at high speeds), optimising drag and lateral dynamics at the same time.

Driving dynamics also benefit from the dynamic roll stabilisation function of the adaptive air suspension system � an innovation in the Q7: the system actively responds to steering movements and thus counteracts body roll.

In addition, the driver can activate two additional modes off-road:
25 millimetres higher than at normal level, the Audi Q7 can reach speeds of up to 100 km/h in the off-road mode. In lift mode, with 60 millimetres of extra ground clearance (absolute value 240 mm), even major obstacles can be negotiated. The automatic function抯 control mechanism intervenes to lower the vehicle抯 centre of gravity to achieve ride comfort and driving dynamics at higher speeds.

A new feature in the Q7 is the facility to lower the body at the touch of a button via the rear axle only. The loading lip is lowered significantly, making it much easier to load items into the luggage area.

The fully-supporting air springs at the front and rear axle keep the body level constant, regardless of the load situation.

Added to this is a quality specific to this air suspension concept: the occupants benefit from a smooth ride at all times, regardless of the load the vehicle is carrying. The firmness of the springs always adapts to the weight of the vehicle.

All driving modes and height levels can be read off the MMI screen. The ride height also appears in the central driver information display.

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Related entries:

Audi Q7 hybrid
Audi Q7 3.0 TDI Refined


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