quattro permanent four-wheel drive

Permanent four-wheel drive with variable distribution of the propulsive power by means of a Torsen interaxle differential ensures that even very high engine output is always converted purposefully into forward movement. If the degree of slip rises as a result of a deteriorating coefficient of friction, the propulsive power is automatically diverted to whichever wheels achieve better traction.

Changes in the road surface and the vehicle's dynamic response are immediately compensated for automatically. Load reversal reactions when braking are minimised by the fact that the engine braking torque is distributed between all four wheels.

4-level air suspension

When it comes to suspension, offering the "best of both worlds" is a seemingly insuperable problem. Because strengths in off-road use become severe drawbacks in road use - and vice-versa.

Driving across rough terrain necessitates ample ground clearance, with the result that the vehicle's centre of gravity is high up. Yet this is detrimental to swift cornering, dynamic stability at high speeds and an economically low drag coefficient.

On the other hand, the low centre of gravity of a vehicle designed with road use in mind means that it will often make contact with the ground if driven over rough terrain. The short spring travel of a conventional passenger car will moreover make for a less than comfortable ride.

The best of both worlds can only be achieved with variable ground clearance. Audi's developers have come up with a flexible solution for the allroad quattro, involving an ingenious, electronically regulated air suspension system for the front and rear wheels. It has been further refined for use in all Audi allroad quattro models.

At speeds of over 130 km/h, the vehicle is automatically lowered from its normal ride height by 2.5 cm. In off-road use, a ground clearance of as much as 20.8 cm can be achieved at a speed of up to 35 km/h. The overhang angles of 19.5 degrees at the front and 23 degrees at the rear make it possible to cross difficult terrain, such as ditches, with reliable ease. A ramp angle of 19 degrees prevents the floor from bottoming when the car is driven over ridges, and a maximum gradient of 60 percent ensures that it can climb even steep slopes with verve. With a tilt angle of 40 degrees, the Audi allroad quattro 4.2 demonstrates excellent stability when driven in an inclined position.

As there is now just a single mode, automatic engaging of the parking level has been eliminated and the changeover speed thresholds have been modified, the 2002 model year marks the advent of a substantially simplified ride height control system. The automatic regulating functions exclude the possibility of operating errors, while still providing scope for manual intervention.

The functions of the 4-level air suspension

The ride height is adjusted automatically when the threshold speed is reached, irrespective of whether the vehicle has been started in the ride height mode indicated or whether the driver has selected that ride height manually while the vehicle is in motion. The maximum ride height 2, affording maximum ground clearance of 208 mm, must always be selected manually.

If a speed of 35 km/h is exceeded, the vehicle is lowered to ride height 1 with 192 mm ground clearance. Above 80 km/h, the standard ride height (167 mm ground clearance) is established; if a speed of 130 km/h is exceeded for at least 30 seconds, the ground clearance is then lowered to 142 mm ("motorway mode").

If the standard ride height is re-established manually after the car has been adjusted automatically to its lowest position, the motorway mode is deactivated. The system will then no longer automatically lower the ride height automatically if the vehicle is recurrently accelerated over the 130 km/h speed threshold.

This avoids the need to keep re-establishing the standard ride height manually or to slow down to at least 70 km/h in order to prompt the change automatically. The motorway mode will not be reactivated until the engine is next turned on.

The vehicle is returned from this low ride height to the standard ride height after an optimised time lapse of 120 seconds if its speed is less than 70 km/h, after 30 seconds at less than 35 km/h, and immediately if it is travelling at below 5 km/h.

If the driver starts the car at the low ride height or selects it manually while on the move, the system does not adjust it automatically according to speed. The current ride height is displayed on the instrument panel.

Tailor-made equipment

The already extensive specification of the Audi allroad quattro has been further upgraded on the new 4.2 version. The eight-cylinder version runs on 7.5 x 18 aluminium hollow-spoke wheels with 245/45 R 18 Y tyres, and sees its way with xenon headlights. On the inside, it has Cricket leather equipment with a four-spoke steering wheel, electrically adjustable front seats with lumbar support and a folding centre armrest. There are in addition inlays in Walnut, the Driver Information System DIS and an anti-theft alarm system.

The standard-fit passive safety equipment includes airbags for the driver and front passenger, side airbags at the front and the Audi Sideguard head-level airbag system.

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