Even more efficient: engines with MHEV technology
At its market introduction in Europe, the new A8 will start out with two extensively reengineered V6 turbo engines. Other engine versions and a plug-in-hybrid with inductive in-car charging will follow in 2018. All engines offer supreme refinement, ample performance and high efficiency. The new mild hybrid technology (MHEV, mild hybrid electric vehicle) drives down fuel consumption even further – by as much as 0.7 liters (0.3 US gal) of fuel per 100 kilometers (62.1 mi) in real driving conditions. Particulate filters for the gasoline engines will also follow in the next year.
Audi’s MHEV technology is based on a newly developed 48-volt primary electrical system – it supplies the 12-volt system that now becomes an electrical subsystem. The 48-volt system is fed by a belt alternator starter (BAS) connected to the engine’s crankshaft by the belt drive. A lithium-ion battery positioned safely beneath the luggage compartment floor serves as the storage unit.
The new drive combines efficiency with comfort in a very special way: Thanks to the higher voltage, the new A8 can coast along silently in a speed range from 55 through 160 km/h (34.2 through 99.4 mph). The automobile then proceeds with zero emissions for up to 40 seconds with the engine off altogether. As soon as the driver steps on the gas again, the belt alternator starter prompts a swift but soft restart. In addition, start/stop operation is actually active from 22 km/h (13.7 mph). When the brakes are applied, the BAS can recover up to 12 kW of power, again helping to reduce fuel consumption.
Comfort and stability: the power transmission
The engines in the A8 deliver their power to a newly developed eight-speed tiptronic. Not only does it change gear swiftly and smoothly; it also operates highly efficiently. An rpm-adaptive torsion damper (RTD) with a centrifugal force pendulum compensates for undesirable vibrations in the engine. This permits efficient driving from an engine speed range as low as 1,000 revolutions per minute.
The improved tiptronic is now for the first time equipped with an electric oil pump – it is activated whenever the large sedan is coasting with the engine off. As soon as the new A8 is coasting and its engine is either deactivated or idling, a clutch in the central transmission is disengaged to interrupt the power flow. For a faster buildup of pulling power, especially after coasting with the engine deactivated, the engineers in partnership with ZF optimized the engagement logic applied in the gearshift process.
The transmission control in the new A8 can for the first time recognize stop & go situations. It now modifies the driving strategy with the emphasis on comfort; for example, it avoids unnecessary gearshifts or starting in second gear. The driver can let the automatic transmission do the work automatically in the E, D and S modes, or can take charge of controlling it in M mode. Selector lever commands are all transmitted electrically.
quattro permanent all-wheel drive is standard in the new Audi flagship model. In normal driving conditions, its self-locking center differential distributes torque between the front and rear axle in a 40:60 ratio. If slip occurs at one axle, it directs up to 70 percent of the drive torque to the front and up to 85 percent to the rear. Handling benefits from wheel-selective torque control whenever a committed driving style is adopted. The intelligent software function brakes the two wheels on the inside of a bend slightly before they can begin to spin.
Customers can also choose the optional sport differential. When cornering dynamically, this redistributes the torque between the rear wheels as required – enhancing traction, stability and dynamics. The driver can view a display of the percentage drive torque per wheel in the MMI of the new A8. Compared with the previous model, the sport differential is around one kilogram (2.2 lb) lighter and offers even faster, higher-precision control. Its management uses the latest generation of the electronic suspension platform (ESP) and is incorporated into the Audi drive select handling system. This allows the driver to experience a range of chassis settings in one and the same car. The operating principle of the participating systems can be set using the comfort, auto, dynamic, efficiency and individual modes.
Inductive in-car charging: Audi Wireless Charging
Audi Wireless Charging (AWC) for the plug-in.hybrid involves a floor pad inducing an alternating current in the secondary coil installed in the car, under the front axle. The magnetic field presents no danger whatsoever – it is only created when the plug-in-hybrid is positioned above the pad and the charging process is active. To facilitate parking for the driver, the MMI shows the position of the charging station. Before the charging process starts at 3.6 kW, the pad is raised to reduce the distance between it and the car, and achieve a high charging efficiency of over 90 percent from mains to battery.
From silky-smooth to firm: the suspension
Active suspension, dynamic all-wheel steering, electronic suspension platform (ESP) – Audi has rethought every aspect of the chassis of its new flagship. Revolutionary technologies and control systems make it even more comfortable, sporty and safe. It spans a whole new breadth of characteristics – from the silky-smooth progress that befits a luxury sedan to the dynamically firm handling of a sports car.
The very fundamentals of its design are state of the art. The front and rear axle, both of them mounted on subframes, take the form of high-precision five-link constructions made extensively from lightweight aluminum. Both the progressive steering, which becomes more direct the further it is turned, and the adaptive air suspension with controlled damping are standard features. The driver can define the air suspension settings using the three Audi drive select driving profiles comfort, auto and dynamic, and also in a separate lift mode. From a speed of 120 km/h (74.6 mph), the body is automatically lowered by 20 millimeters (0.8 in) for improved aerodynamics. For this to take place, the car must have been running in the auto or dynamic mode continuously for at least 30 seconds.
A new dimension of flexibility: the Audi AI active suspension
Adaptive air suspension already gives the A8 a wide spread of operating characteristics ranging from smooth ride comfort to sporty handling. This impression is heightened engagingly with Audi AI active suspension, which will be available from market launch. Audi AI active suspension is a fully active, electromechanically operated suspension system. For each wheel there is one electric motor supplied by the 48-volt primary electrical system. In each case there is also a transmission, a rotary tube housing a titanium roll bar and a lever that exerts up to 1,100 newton-meters (811.3 lb-ft) on the suspension via a coupling rod.
A new feature in active suspension is that the load can be increased or reduced individually on all four wheels, for active control of the body in every driving situation. This introduces a new dimension of flexibility: If the driver selects the dynamic mode in the Audi drive select system, the new A8 becomes an agile sports car – it turns in firmly, and its roll angles are roughly halved compared with the normal status. By contrast, in comfort mode, the body floats smoothly even over rough bumps in the road.
As well as improving comfort and handling, active suspension in combination with crossing assist improves passive safety in the event of a lateral collision. In an impending lateral collision at more than 25 km/h (15.5 mph), the suspension actuators raise the body on the side exposed to the danger by up to 80 millimeters (3.1 in) within half a second. The aim is to present an even more resistant section of the body to the other party by way of an impact zone. The side sills and floor structure accommodate a large portion of the impact forces. Deformation of the cabin and the loads acting on the occupants, above all to the chest and abdomen areas, can be reduced by up to 50 percent compared with a lateral collision with no raising of the suspension. The pre sense 360° system is a requirement for the new function.
Boundaries pushed: dynamic all-wheel steering
There is another world first in the suspension of the new A8: dynamic all-wheel steering. It, too, is controlled by the electronic suspension platform (ESP). The new steering system approaches the steer angle and directional stability as separate issues, once again probing the boundaries of the physically possible. At low speeds and on tight bends, the luxury sedan significantly reduces steering effort. But this is never allowed to unsettle it. The A8 is even unruffled by an abrupt lane change at high speed. The driver always feels intensive, finely differentiated feedback from the road.
The optional dynamic all-wheel steering combines two distinct high-tech steering systems. The dynamic steering on the front axle incorporates what is known as strain wave gearing where the ratio changes as a function of speed. The rear wheels are turned by a spindle drive and two track rods – at low speeds by up to five degrees against the direction of steering, to facilitate maneuvering and reduce the turning circle by about one meter to 11.4 meters (37.4 ft) on the A8 or 11.8 meters (38.7 ft) on the A8 L. At medium and high speeds, the wheels are turned by up to two degrees in the direction of steering, for increased stability. Dynamic all-wheel steering matches the steering ratio optimally to the driving situation, adjusting the ratio across a range of 9.5 to 17. At the limits of driving dynamics or on surfaces that are slippery under one side of the car, dynamic all-wheel steering again stabilizes the new A8 by manipulating the steering at the front and rear axles.
Intelligent and highly integrated: the electronic suspension platform (ESP)
The second generation of the ECP features in the A8. It brings together all signals and data relating to the suspension in a single control unit and offers a new function with the integral driving dynamics controller. It influences the dynamic all-wheel steering, sport differential and active suspension – a new level of integration in the luxury class. The sensors also detect the driving status, such as understeering or oversteering, and the road surface friction. The control unit uses the calculated values to adjust the above components as well as the damper control and air suspension. The customer experiences this in the form of optimum cornering behavior, improved transverse dynamics and ideal ride comfort. The combined algorithms allow faster, more in-depth coordination of the individual systems.
Large and powerful: the wheels and brakes
The powerful brakes with their aluminum fixed calipers on the front axle also make a big contribution to driving safety. Each caliper on the front wheels has six brake pistons. Electronic Stabilization Control provides even more precise control than in the previous model. The wheel range starts with an aerodynamically optimized 17-inch wheel, going all the way up to size 9 J x 21 with 275/35 tires. If any of the wheels are not properly tightened, a function integrated into the Electronic Stabilization Control alerts the driver promptly. The loose wheel warning is standard, and unique in the market.
A new level of intelligence: Audi AI
Audi AI is the umbrella term for a new generation of high-end assistance technologies extending all the way up to highly automated driving. Three of them will be available for the first time in the new A8 – the Audi AI traffic jam pilot, the Audi AI (remote) parking pilot and the Audi AI remote garage pilot.
World debut for highly automated driving: the Audi AI traffic jam pilot
With the Audi AI traffic jam pilot, the brand with the four rings presents the world’s first system that enables highly automated driving at Level 3. The car takes over the task of driving in certain situations. Unlike at Level 2, the driver no longer needs to monitor it permanently. They must merely be capable of taking back responsibility whenever the system prompts them to.
The driver activates the traffic jam pilot with the AI button on the center console. On freeways and highways where a physical barrier separates the two carriageways, the system takes over the driving task in traffic jam and slow-moving traffic at up to 60 km/h (37.3 mph). In these situations the traffic jam pilot manages starting, accelerating, steering and braking. It can also handle challenging constellations such as vehicles cutting in closely in front. The signals that the traffic jam pilot needs for highly automated driving are supplied for instance by the central driver assistance controller (zFAS).
hands off the steering wheel permanently and, depending on national laws, focus on a different activity that is supported by the vehicle infotainment system. In this instance the Audi virtual cockpit supplies abstract representations that symbolize the motion and surroundings of the new A8.
During highly automated travel a small camera in the driving area detects if the driver tires or falls sleep. If that happens, a multi-stage warning is given. As soon as the speed rises above 60 km/h (37.3 mph) or the line of vehicles breaks up, the traffic jam pilot informs the driver that they need to take charge of driving once again. If they ignore this prompt and the subsequent warnings, the new A8 is braked to a standstill. The introduction of the Audi AI traffic jam pilot means the statutory framework will need to be clarified in each individual country, along with the specific definition of the application and testing of the system. The brand’s high quality standards are equally applicable in the realm of highly automated driving. In addition, a range of approval procedures and their corresponding timescales will need to be observed worldwide. Audi will therefore be adopting a step-by-step approach to the introduction of the traffic jam pilot in production models.
Park and watch: the Audi AI remote parking pilot and garage pilot
With the Audi AI remote parking pilot and the Audi AI remote garage pilot, the A8 drives independently and without a driver into a parallel or right-angle parking space in several maneuvers, or forward into a garage. Both systems access the steering, accelerator, brakes, tiptronic and also the optional dynamic all-wheel steering.
What is new here is the driver is outside the car throughout the entire parking maneuver. They start the maneuver from their smartphone by pressing the Audi AI button in the myAudi app. To monitor it, they hold it pressed and watch a live display from the car’s 360 degree cameras on their device. Once the parking maneuver is over, the system automatically engages the tiptronic P position and switches off engine and ignition. When ready to drive off, the driver can start their A8 by smartphone and drive it out of the parking space or garage again. If the driver is still behind the wheel, they also have the option of activating the parking pilot using the AI button in the center console. Like the AI button in the myAudi app, they again need to hold it pressed throughout the entire process.
The Audi AI (remote) parking pilot and the Audi AI remote garage pilot function intelligently and conveniently. For instance the sedan can also be steered accurately into a garage if it needs to describe an arc. Inside the garage, the A8 can approach very close to the walls and obstructions such as bikes – or it will interrupt entering if there is not enough space for the car. This special function benefits especially from the innovative laser scanner and is not available in any other competitor model.
The equipment, data and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.