Driveline
The new A4 is being launched with a choice of five powerful, refined engines. All of them, both petrol and diesel, use direct fuel injection, and the two four-cylinder units and the V6 TDI engines are turbocharged. With their splendid flow of power, these engines make driving the new A4 nothing less than pure pleasure. They also use less fuel than the equivalent engines in the previous model. Customers furthermore have a wide choice of high-tech transmissions: either a manual gearbox or automatic transmission can be specified. They transmit power to the front wheels or to a quattro permanent all-wheel driveline that has particularly dynamic settings.
Like the TDI diesels, the two petrol engines, the 3.2 FSI and the 1.8 TFSI, use the direct injection principle, in which fuel is delivered directly to the engine’s combustion chambers. When this fuel vaporises, it absorbs heat from the combustion chamber walls, which allows the engine to operate at a higher compression ratio. Its overall efficiency is thus higher – power and efficiency go together in every Audi.
The new 3.2 FSI, a member of Audi’s ultra-modern family of V engines, is the most powerful unit available in the new A4. From a displacement of 3197 cc, it develops 195 kW (265 bhp) and also delivers 330 Nm of torque all the way from 3000 to 5000 rpm. It accelerates the A4 3.2 FSI quattro with manual gearbox from a standstill to 100 km/h in only 6.2 seconds, and maintains this flow of power until the governed top speed of 250 km/h is reached. As an alternative from 2008 onwards, this engine can be combined with the 6-speed tiptronic automatic transmission; in either case, it delivers its power to the road via quattro permanent all-wheel drive.
The engine’s inlet valves are actuated by a pioneering innovation: the Audi valvelift system (AVS). It uses sliding sleeves (cam elements). These have different profiles, one alongside the other. They are slid along the camshafts in order to obtain smaller and larger amounts of valve lift.
The purpose of AVS is to ensure that the combustion chambers are always ideally filled; the throttle butterfly can then remain fully open in most cases, so that the engine breathes more efficiently.
The Audi A4 3.2 FSI with manual gearbox is content to consume an average of only 9.2 litres per 100 kilometres, 1.2 litres fewer than the previous car with a 188 kW (255 bhp) engine. About half of this improvement is due to the new valve actuating principle; the other half has been achieved by minimising internal friction. Oil pump volume is now smaller, with an optimised loss rating. Like the water pump, it now delivers a demand-controlled flow – another means of reducing fuel consumption.
The smaller of the two petrol engines, the compact four-cylinder 1.8 TFSI, is a highly efficient unit that develops 118 kW (160 bhp) and a torque of 250 Nm between 1500 and 4500 rpm from a displacement of 1798 cc. It accelerates the manual-gearbox A4 in 8.6 seconds to the typical main-road speed of 100 km/h, and maintains its thrust up to a top speed of 225 km/h. Yet according to the EU test cycle its consumption is only 7.1 l/100 km –1.1 litres per 100 kilometres better than the previous model. As an alternative to the manual gearbox, multitronic continuously variable transmission can be ordered, in both cases with front-wheel drive.
The 1.8 TFSI is a close relative of the 2.0 TFSI engine chosen three times in succession by a jury of international journalists as “Engine of the Year”. On this smaller version for use in the latest model line, direct petrol injection and turbocharging represent an ideal combination. Injection pressure has been increased to 150 bar, and new injectors distribute the fuel accurately to the combustion chambers. The turbocharger is exceptionally rapid in its response – at an engine speed of 2000 rpm it accelerates the engine 30 percent faster to a ten percent higher torque than the conventional 1.8T engine that powered the preceding model. For all its vigour, this four-cylinder unit runs quietly, in a most refined manner.
Supreme pulling power – the TDI engines
The three diesels for the new Audi A4 are two V6 units and a four-cylinder inline engine. Their strong performance makes them ideal representatives of a modern, powerful form of sporting character. Winning the Le Mans 24-hour race in 2006 and 2007 with the Audi R10 competition car was ample evidence of the power that can be summoned up by the TDI principle. Audi first introduced this efficient technology back in 1989, and it has remained the most efficient in the world to this very day. Since then, the brand with the four-ring emblem has not ceased to develop its technological lead.
The three-litre diesel is a new member of Audi’s V-engine family. It develops 176 kW (240 bhp) and has a peak torque of no less than 500 Nm all the way from 1500 to 3000 rpm. This large TDI unit, with its displacement of 2967 cc, makes the new A4 even more of a sports saloon. It needs only 6.1 seconds to accelerate to 100 km/h from a standing start, and has a top speed of 250 km/h, yet its average fuel consumption is a more than modest 6.9 l/100 km. The 3.0 TDI always has quattro permanent all-wheel drive.
The V6 TDI’s engine block is made from a light but rigid high-tech material: vermiculite graphite cast iron. Inside the engine, intensive fine tuning measures have minimised friction losses. The latest generation of common-rail fuel injection is used. Its high operating pressure atomises the fuel extremely finely, for a more uniform mixture and efficient combustion. The piezo injectors operate with immense speed and permit the fuel injection stroke to be divided up into individual stages, so that the engine runs exceptionally smoothly.
The exhaust-driven turbocharger is also a unit from the latest design generation. A high-speed actuating motor alters the position of its guide vanes, so that high torque builds up more rapidly and spontaneously. The 3.0 TDI already complies with forthcoming Euro 5 limits. A novel exhaust gas recirculation concept with increased cooling performance is used to reduce emissions of oxides of nitrogen.
The 2.7 TDI engine, with a displacement of 2698 cc, has been derived from the 3.0 TDI, and also complies already with the future Euro 5 exhaust emission limits. Its output is 140 kW (190 bhp) and it develops up to 400 Nm of torque between 1400 and 3250 rpm. As a result the A4 2.7 TDI sprints to 100 km/h from a standstill in 7.7 seconds and can reach a top speed of 226 km/h. Its average fuel consumption, on the other hand, is a modest 6.6 litres per 100 kilometres. The standard specification of this model includes multitronic continuously variable transmission and front-wheel drive – an ideal combination for relaxed, effortless driving.
Powerful and refined – the 2.0 TDI
The four-cylinder TDI engine, with a displacement of 1968 cc, is a new interpretation of the strengths of the TDI concept. The piezo injectors of its common-rail fuel injection system operate at a maximum pressure of 1800 bar. Other innovative design features relate to the turbocharger, the toothed belt camshaft drive and the geometry of the pistons.
This two-litre engine develops 105 kW (143 bhp) and has the powerful peak torque of 320 Nm between 1750 and 2500 rpm – figures that explain why the new Audi A4 can accelerate from 0 to 100 km/h in 9.4 seconds and reach a top speed of 215 km/h. When combined with the six-speed manual gearbox, the 2.0 TDI is content with an average fuel consumption of 5.5 l/100 km, in which case the 65-litre fuel tank provides an action radius of more than 1,100 kilometres. The four-cylinder TDI can also be ordered with the multitronic continuously variable transmission. In both cases the front wheels are driven.
The 2.0 TDI also outperforms the Euro 5 exhaust emission limits. Thanks to improved thermodynamics, it can operate at a higher rate of exhaust gas recirculation, so that untreated emissions of oxides of nitrogen are lower. The cooler combustion process, with less oxygen present, would normally have an adverse effect on efficiency, but by careful attention to detail the development engineers have managed to transform this into an improvement in fuel consumption.
Transmissions: a wide choice
Sporty road dynamics and large-car comfort – these were also the overall objectives for the new A4 pursued by Audi’s transmission developers. The manual gearbox is a new design; the tiptronic six-speed automatic and multitronic continuously variable transmissions have been intensively revised and improved. All these transmissions are notable for their ease of operation and high efficiency, with short, precise lever or selector travel. The transmission layout has been changed for the new A4: the differential is located immediately behind the engine and is therefore now ahead of the clutch or torque converter.
Audi uses two types of six-speed manual gearbox on the new model, depending on the required load capacity. Numerous measures have been taken to reduce internal friction. All manual-gearbox versions of the new A4 have a gear indicator integrated into the Driver Information System display. It shows which gear is currently selected and also informs the driver if a different gear would help to reduce fuel consumption.
The new A4 3.2 FSI will be available later with 6-speed tiptronic automatic transmission as an alternative to the manual gearbox. The tiptronic transmission has been extensively revised. It responds more rapidly than on the previous model, with shorter shift times, but its high standard of refinement has nonetheless been retained.
For the 2.7 TDI, Audi can supply the multitronic continuously variable transmission; this will also be available in the 1.8 TFSI and 2.0 TDI from 2008 onwards. Its power losses, already very slight, have been reduced still further by a number of improvements. The new variator provides wider-spaced ratios. Thanks to a particularly low drive-off ratio, the A4 with multitronic sprints away vigorously from a standstill. When accelerating in the dynamic Sport programme, eight successive ratios are selected by way of fixed, programmed characteristics, for sporty performance. In the manual selection mode, the driver can select these eight ratios as he or she prefers.
Audi has a sporty trendsetter in its portfolio: quattro permanent all-wheel drive. The additional traction, dynamism, driving safety and directional stability it provides are clues to Audi’s proverbial technological lead, as summed up in its slogan ‘Vorsprung durch Technik’. For the new A4, this driveline has a 40:60 torque split and therefore distributes power to the wheels in a sportier, more fascinating way than ever before. The 3.2 FSI and 3.0 TDI have the quattro driveline as standard equipment.
The key element in the quattro driveline for the new Audi A4 is a self-locking centre differential. It has an entirely mechanical action and reacts instantly to changes in the driving situation, thus contributing to the car’s sporty, agile road dynamics. In normal driving conditions, it directs 40 percent of engine torque to the front wheels and 60 percent to the rear, but whenever the need arises, the self-locking centre differential takes effect and transmits more torque to the axle with better traction. In this way the new Audi A4 often masters situations close to the traction limit without the ESP/EDL having to intervene, and even if these systems are in action, brake applications are much less frequent.
Running gear
The new A4’s dynamic suspension combines sporty precision with high stability and supremely confident road behaviour. It is a totally new design, with many components made from aluminium in order to reduce unsprung weight. Two technological breakthroughs make the driving experience even more fascinating: adaptive shock absorber control and Audi dynamic steering.
The Audi dynamic steering system alters its effective ratio according to road speed, and helps to keep the new A4 stable when the handling limits are approached by making slight but extremely rapid steering corrections. The adaptive shock absorber control maintains optimal tyre contact with the road, for safety allied to dynamism in just about every situation, and so that even the enthusiastic driver can be sure that maximum safety is always available.
Interchanging the differential and the clutch has enabled the front axle to be moved forward by 154 millimetres. This change, aided by moving the car’s battery to the boot, helps to achieve ideal weight distribution.
With its wide track –1564 mm at the front, 1551 mm at the rear – the A4 suggests its dynamic power even at a standstill. To drive it is to experience the sportiest car in the midsize category: agile, effortless to handle and safe at all times. With its almost neutral steering response, the new A4 can be cornered at high speeds.
Strong structural members – rapid build-up of forces
The front axle pivot bearings and the five links that locate each front wheel are made of aluminium. At the front of the A4, the engine and suspension support beam is also made of aluminium, and bolted rigidly to the body.
The steering gear is located low down and well forward, with the track rod transmitting steering movements directly to the wheels. Rack and pinion steering provides well-defined, sensitive feedback from the road but transmits in effect no undesirable jolts or shake. The steering ratio of 16.1:1 is sporty and direct, but never nervous in its response. The controlled-output pump only delivers the amount of power steering oil actually needed; this lowers fuel consumption by about 0.1 l/100 km. Cars with V6 engines are equipped as standard with power steering that varies the degree of assistance according to road speed.
The development engineers based the design of the rear suspension on the controlled toe-angle principle with trapezoidal links used for the larger A6 and A8 model lines; this is a space-saving layout that combines sporty handling with a high level of ride comfort.
Applying the lightweight construction principle, the steel axle beam is attached to the body by four rubber bushings; these are very rigid laterally to ensure dynamic handling, but softer longitudinally for greater vertical and lengthwise compliance. The trapezoidal links, wheel carriers, upper wishbones and track rods are all made of aluminium. The well-proven solution comprising separate spring and shock absorber mountings, and in particular the new spring connection points at the wheel carriers, ensure good initial suspension response.
Versions of the new A4 with engine outputs up to 118 kW (160 bhp) run on pressed-steel wheels with full-size wheel covers and 205/60 R16 tyres. Cars with more powerful engines have elegant alloy wheels and 225/55 R16 tyres. Optional extras are also available from quattro GmbH: 18-inch wheels with 245/40 tyres and also 19-inch wheels. 8 J x 17 wheels can be obtained with run-flat tyres. Standard equipment on cars with a V6 engine is a tyre pressure monitoring display that operates extremely accurately and reliably.
Powerful stopping too – the brake system
Behind the car’s big wheels are brakes with 314 mm diameter front and 300 mm rear discs; the front discs are internally ventilated. The high-performance brake pads, a new development, now cover 20 percent more rubbed area. The front brakes on V6-engined cars are even larger, with 320 mm discs and composite spheroidal-graphite and aluminium callipers. In every version of the A4, the brake pedal has a firm, precise action, and thanks to accurate feedback the driver can control the brake application effectively without applying excessive pressure.
The latest generation of ESP stabilisation system adds to the operating refinement of the brake system. New hydraulic valves build up pressure with exceptional accuracy, and the regulating action takes place without judder. At speeds below 70 km/h, the driver can disconnect certain anti-slip functions by pressing a button briefly. The wheels can then spin, but this can be beneficial in certain circumstances, for instance when driving on snow.
ESP in the new A4 has a number of additional functions – it can for instance stabilise a trailer if it begins to snake, dry the brake discs in wet weather and activate the hazard warning flashers if a panic brake application is made.
Audi drive select – up to four different cars in one
Those who drive the A4 hard and enthusiastically can choose between two sports suspension settings, or alternatively rely on an innovative technology – the innovative system known as Audi drive select. This is available in various stages, which influence an increasing number of technical components and functions on the car: accelerator pedal response, tiptronic shift points, power steering assistance, the steering ratio and the action of the electronically adjustable shock absorbers – another new feature.
The driver can select the comfort, auto or dynamic modes at switches on the centre console. If the A4 is equipped with the MMI control system, a fourth mode, “Individual”, is available; this enables an individual profile of 24 settings to be configured. Audi drive select transforms a single A4 into up to four different cars – a range of driving pleasure, dynamism and ride comfort that is unmatched in the midsize car category.
As fast as a professional rally driver –Audi dynamic steering
The new A4 features yet another pioneering technological development: Audi dynamic steering. Its key element is a superimposed gear system that alters the overall ratio according to road speed and the chosen Audi drive select setting. This concentric-shaft steering gear is extremely compact and light in weight; it has a precise action free from any slack. It was first developed for use in robots and for space travel applications; the expedition vehicles on which it was installed have already traversed the surface of the moon and Mars.
Audi dynamic steering makes the steering ratio more direct at low speeds, with a higher level of power assistance. This renders the steering extremely light when manoeuvring, and only two turns of the wheel are needed from lock to lock. As the car’s speed increases, however, the steering ratio becomes gradually less direct and in parallel with this the amount of power assistance is reduced. At high motorway speeds the A4 can therefore be driven smoothly and has excellent straight-line stability.
Audi’s high-tech steering can do even more. It is closely networked with the ESP and therefore receives precise information about the car’s attitude as the handling limit is approached. If the A4 threatens to oversteer, for instance after an abrupt avoidance manoeuvre, the steering performs slight corrective impulses in the direction needed to reduce this tendency. Such corrective action takes place faster than even an experienced rally driver could react. This rapid response means that brake applications are often not needed, so that the car continues its journey more smoothly and dynamically.
The system also takes action if the car understeers: it selects a more indirect steering ratio for a short time, the aim being to prevent the driver from turning the steering beyond the point at which the tyres still have plenty of road grip. With these capabilities, Audi dynamic steering represents leading-edge technology in this car market segment.
The optional-extra damping control permits individual suspension settings to be chosen. These are based on the lowered sports suspension. Continuously adjustable hydraulic shock absorbers permit the damping characteristic to be varied individually at each wheel. This means optimal contact between the tyre and the road in almost every situation, for greater safety and more dynamic road behaviour.
Equipment and trim
The new Audi A4 can be ordered ex factory with one of four equipment and trim specifications, all of them with a very full list of items. The new saloon model, however, can be further enhanced by choosing from a selection of luxury optional extras. Its innovative assistance systems and the broad range of electronic components are taken directly from the large luxury car programme.
The four equipment and trim lines have been named Attraction, Ambition, Ambiente and S line, and each of them can be ordered with any of the available engines. Even the Attraction line gives the new A4 a high level of comfort and convenience. 16-inch wheels emphasise its sporty character, and the daytime driving lights give it a striking presence on the road. Automatic boot lid opening, the electro-mechanical parking brake, the 6.5-inch black-and-white display screen and the automatic air conditioning all add to the high standard of comfort and convenience, and the ‘chorus’ radio with MMI control logic has a CD player and eight loudspeakers.
Ambition, the second equipment and trim line, is sporting in character. Its most obvious feature are 17-inch diameter cast aluminium wheels of six-spoke design. Sports suspension, which the customer need not specify if not required, makes the handling even more dynamic, and the three-spoke leather-covered sports steering wheel is a striking feature of the interior.
The third equipment and trim line is Ambiente, which focuses on comfort. The A4 then runs on specially designed 16-inch cast alloy wheels of seven-arm pattern. The front seats can be heated. The Audi parking system makes parking in reverse easier and cruise control maintains a constant road speed when required. Other features for extra comfort and convenience are the multifunctional leather-covered steering wheel and a front armrest with two power sockets; the lighting package adds further highlights.
Customers with a dynamic approach to driving will tend to favour the sporty S line, which offers an exterior design package and a sports package. Among its most attractive items are visual changes inside the car, extra-firm suspension settings, 18- or 19-inch alloy wheels and two exclusive colours: Misano red and Monza silver.
Multimedia in the car – a technology area of the future
Audi has a complete system of modular elements to offer in the communication and infotainment area. The first stage above the standard ‘chorus’ radio offers an upgrade to the ‘concert’ or ‘symphony’ systems. Both are from the new generation of audio equipment and operate in conjunction with a 6.5-inch display screen. The controls for both systems – a turn-and-push knob and large switches that can be operated intuitively – use the much-praised MMI logic principle. Both these radios include a double tuner, and the DAB digital broadcasting standard is available if required. A six-CD changer is integrated into the ‘symphony’ radio.
An optional extra for both systems is a lifestyle feature that looks well ahead into the future: the Audi Music Interface (AMI). It has iPod capability, with the menu structures visible on the car’s display screen. Music from other players can also be listened to by way of the AMI interface.
‘Wellness for the ears’ from Bang & Olufsen
The next two system stages feature the MMI Basic plus or standard navigation system with DVD including MMI. In these cases, all the system’s controls are moved to the MMI control terminal. MMI Basic plus has a black-and-white screen with arrow display and an integral audio CD changer.
The full version of the navigation system with DVD including MMI incorporates a double tuner and a 7-inch colour screen, with navigation information taken from a DVD drive. The high-end system can be extended to include voice control, the Audi Music Interface and a digital TV tuner.
For perfection in sound reproduction, Audi can offer two high-class audio systems. The Audi Sound System has a 180-Watt rating and ten loudspeakers. The ultimate choice, however, is the Sound System from Bang & Olufsen. Brilliant high notes, authentic detail resolution, precise sound stage reproduction and a broad, subtly differentiated frequency spectrum – this product from the Danish audio champions satisfies every demand for top precision and quality. A 505-Watt amplifier transmits its signals according to a surround algorithm developed specially by the manufacturer, permitting the full sound experience to be enjoyed at every seat in the car. This system has ten active channels with 14 loudspeakers.
Bluetooth: the perfect link to the mobile phone
The two MMI systems both allow a mobile phone to be integrated in a very elegant manner with Bluetooth. If the driver’s mobile phone supports the SIM Access Profile, it only needs to be logged into the A4’s system once. The car’s system then performs all the available functions automatically as soon as the driver inserts the ignition key. The mobile phone can remain in the driver’s pocket; the A4 phone can access all the data from the SIM card and the internal memory. The mobile phone then shuts down, so that its battery is not drained.
The Bluetooth car phone uses the car’s own aerial and is operated by voice input, via the MMI or at the multifunctional steering wheel. A digital speech processor ensures the best possible hands-free quality. Output is via the Sound System, using the radio volume control.
Innovative driver assistance systems
Audi has developed a wide range of assistance systems that bring large-car luxury to the midsize category. The Audi parking system advanced uses a rearview camera to simplify parking. What the camera sees is shown on the monitor screen of the MMI control system, together with various guide lines and panels to help in positioning the car.
Staying in lane – with Audi lane assist
Audi lane assist is a lane monitoring system that operates above about 65 km/h and warns the driver if he or she departs from the chosen lane. A miniature camera on the windscreen views the road ahead and a computer identifies the lane lines. If the car moves toward a lane line without the driver having made a turn signal, Audi lane assist warns him or her by means of vibration at the steering wheel. Vibration intensity and the point at which the warning starts can be selected in three stages.
Radar looks back – Audi side assist
Audi side assist is specifically intended for situations in which the driver wishes to change lanes. Two radar sensors in the rear bumper scan the area behind and alongside the A4; their signals are evaluated by a computer. If another vehicle is moving at the same speed in a critical area or approaching fast from behind, an LED display comes on in the outside mirror housing as a warning which the driver identifies subconsciously.
If the driver operates the flashing turn indicator, the system interprets this as a sign that he or she still intends to change lanes. The light-emitting diodes then become brighter and flash for about one second at a higher frequency. This warning is extremely difficult to ignore. Audi side assist is in action above a road speed of 60 km/h.
Relaxed driving in dense traffic – adaptive cruise control
Another assistance system that has initially been available only on luxury cars is radar-assisted adaptive cruise control (ACC). It normally maintains any preselected speed between 30 and 230 km/h, but can vary it by taking the distance from the vehicle ahead into account. The radar signals scan an area 180 metres long and cover an angle of eight degrees. The computer analyses them to determine whether and to what extent the distance from the vehicle ahead is changing.
The A4 driver selects the desired speed and chooses one of the programmes that determine the time gap from the vehicle ahead and the regulating dynamic. The system keeps the vehicle at the necessary speed by accelerating or braking as the need arises, but with the occupants’ comfort also taken into consideration. The rate of retardation when braking is not allowed to exceed 3 m/s2 at 50 km/h or higher.
In certain situations, for instance if the driver ahead brakes sharply and suddenly, this automatic speed reduction may be insufficient. In such cases Audi braking guard, one of the functions included in the ACC, takes over. It calculates whether sufficient time remains available to steer round the obstacle ahead, and allows the driver a few moments to take the necessary action. If the driver does not react, he or she is called upon by an audible warning signal and red flashing lights to apply the brakes.
If the driver still does not react correctly, the Audi braking guard brakes the car sharply for a brief moment. This lasts no more than 0.3 of a second and causes the speed of the A4 to drop by a maximum of 5 km/h. This abrupt braking action ‘rouses’ the driver. If he or she now makes an emergency brake application, the brake assistant will support it by ensuring that full braking pressure is immediately available.
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