Mighty Diesel Power: the Audi SQ8 TDI

Audi presents the sporty top model of the Q family: the SQ8 TDI (combined fuel consumption in l/100 km: 7.8 (30.2 US mpg); combined CO₂emissions in g/km*: 205 – 204 (329.9 – 328.3 g/mi)). Thanks to the eight-cylinder diesel engine with biturbo charging, the large SUV coupe offers superior performance coupled with a high level of efficiency. The drive and suspension technologies, which include the sport differential, roll stabilization and all-wheel steering, ensure dynamic handling. The Audi SQ8 TDI will be on the lots of European dealerships in the late summer of 2019. Its price in Germany starts at 102,900 euros.

Power and efficiency: 4.0 TDI with electric powered compressor
The biturbo V8 in the Audi SQ8 TDI (combined fuel consumption in l/100 km: 7.8 (30.2 US mpg); combined CO₂ emissions in g/km*: 205 – 204 (329.9 – 328.3 g/mi)) is the most powerful diesel engine on the European market. It provides 320 kW (435 metric hp) and develops 900 Nm (663.8 lb-ft) of torque between 1,250 and 3,250 rpm. This allows the 4.0 TDI to accelerate the large SUV coupe like a sports car: The 100 km/h (62.1 mph) mark is reached after 4.8 seconds, and the SQ8 TDI only reaches its electronic propulsion limit at 250 km/h (155.3 mph). The immense power of the diesel engine is generated by an eight-speed tiptronic and the quattro permanent all‑wheel drive.

An electric powered compressor (EPC) supplements the work of the two turbochargers when starting off and when accelerating at a low engine speed, allowing the V8 TDI to always build up its power spontaneously. The EPC draws its drive power from a 48-volt electrical system, which is also the backbone of the mild hybrid system (MHEV). Its belt alternator starter can recuperate during deceleration and feed power to the lithium-ion battery. In real-world customer operation, MHEV technology reduces consumption by up to 0.5 liters (0.1 US gal) per 100 kilometers. In the WLTP cycle, the large SUV coupe consumes an average of 7.8 liters (30.2 mpg), which corresponds to 205 – 204 grams of CO₂ per kilometer (329.9 – 328.3 g/mi)*.

High-end features: the suspension
As standard, the Audi SQ8 TDI is equipped with the Audi drive select dynamic handling system and the adaptive air suspension sport with regulated damping. The air suspension varies the level position of the body by up to 90 millimeters (3.5 in), thereby allowing the vehicle to be driven on different types of terrain. Three optional top technologies, including the sport differential, provide additional vehicle dynamics, traction and stability. When the vehicle is cornering at high speed, the sport differential actively distributes drive torque between the rear wheels, adding a self-locking center differential to the quattro drive. All-wheel steering is available as an alternative to the standard progressive steering. At low speed, it turns the rear wheels in the direction opposite that of the front wheels to increase agility. As from a speed of approx. 60 km/h (37.3 mph), they turn slightly in the same direction to improve stability.

The third high-tech element is the electromechanical active roll stabilization. There is a compact electric motor between the two halves of the stabilizer on each axle. When driving straight ahead, they largely act independently of each other, which reduces sprung mass vibrations on uneven roads. At sporty paces, however, the stabilizer halves work as a unit by being turned in opposite directions. This makes the handling of the SQ8 TDI tighter and significantly reduces its roll angle when cornering.

S-specific details: the design
In short, the design of the Audi SQ8 TDI can be described as impressive, sporty, and robust. The characteristic exterior elements are accentuated specifically and emphasize the special status of the top model: The octagonal Singleframe is structured by double louvers and surrounded by a large matt silver frame. The underbody protection gleams in the same color and makes the front and rear bumpers appear even more voluminous. The air inlets with their clear contours, the S-specific exhaust system and the distinct quattro blisters above the wheel arches also demonstrate power par excellence. The wheel arches house 21 inch wheels as standard, and exclusive 22 inch wheels are available upon request. Horizontal lines, for example the light strip at the rear and an eye-catching strip above the black diffuser, emphasize the width of the SUV coupe. Standard LED headlights that include high-beam assist illuminate the road, with HD matrix technology available as an option.

As is typical for an S model, the interior is kept in dark colors. The standard sport seats are decorated with an S embossing and contrasting stitching. The S-sport seats plus with integrated head restraints and high side bolsters, which can be equipped with climate control and massage functions as an option, can be fitted upon request. Covers in rotor gray or arras red underline the vehicle’s sporty character. The inlays are made of matt brushed aluminum; carbon or oak are available as alternatives.

Intelligently connected: controls, infotainment, and driver assistance
In line with the sporty interior, the standard Audi virtual cockpit offers S-specific views with red graphical details. The driver can select a performance layout where the central focus is the tachometer, displayed as a square graph, and the performance and torque are shown as percentages. Two large touchscreens with haptic and acoustic feedback function as the main control elements. Alternatively, the driver can use the natural language control feature that understands freely formulated commands and questions. To respond to these, the system accesses information stored in the vehicle as well as the knowledge in the cloud. Amazon’s virtual assistant Alexa, which is fully integrated in the MMI operating system, is a new feature.

As standard, data transfer in the SQ8 TDI takes place via the standard LTE Advanced, which is part of the MMI navigation plus along with the Wi-Fi hotspot and the Audi connect services. The route planning feature offers many clever functions. For example, it recognizes the driver’s preferences based on previous journeys and can therefore make intelligent suggestions. The navigation function is enhanced by Car-to-X services such as traffic sign and hazard information. They use the swarm intelligence of the Audi fleet as well as the latest service, traffic light information. Audi is rolling out this feature step by step in selected European cities. The car receives data from the traffic light central computer, allowing the driver to choose their speed to match the next green light. While waiting at a red light, the Audi virtual cockpit shows the remaining time until the next green light. The system thereby contributes to a predictive and efficient driving style and facilitates a steady flow of traffic.

The adaptive cruise assist makes the journey even more safe and relaxed by assisting with longitudinal and lateral guidance. It incorporates the functions of adaptive cruise control, traffic jam assist and active lane assist. In conjunction with the efficiency assistant, the system predictively slows down and accelerates the Audi SQ8 TDI on the basis of sensor information, navigation data and road signs. In the city, systems such as the intersection assist, rear cross traffic assist, exit warning and the 360 degree camera add to the extensive portfolio.

The new Audi SQ8 TDI

Drive system

• 4.0 TDI V8 engine with biturbo charging, 320 kW (435 metric hp) and 900 Nm (663.8 lb-ft) of torque; 0 to 100 km/h (62.1 mph) in 4.8 seconds; top speed electronically governed to 250 km/h (155.3 mph); combined fuel consumption in l/100 km: 7.8 (30.2 US mpg); combined CO₂ emissions in g/km: 205 – 204 (329.9 – 328.3 g/mi)) (depending on the tires and alloy wheel rims used)
• 48-volt main electrical system with electric powered compressor for fast power build-up even at low engine speeds and mild hybrid system for reducing consumption
• Power transmission via eight-speed tiptronic and quattro permanent all-wheel drive

Suspension

• Progressive steering, sport air suspension and Audi drive select dynamic handling system as standard
• As an option:
  • All-wheel steering with steerable rear wheels for high agility at slow speeds and confident stability at higher speeds
  • Electromechanical active roll stabilization for an even greater spread between smoothness of build-up and sporty handling
  • Sport differential for active torque distribution between the rear wheels
• 21-inch and 22-inch light alloy wheels from Audi and Audi Sport
• Electronic chassis platform for connecting the adjustable chassis systems

Design and interior

• Exterior with sporty design details, including the Singleframe with double louvers, striking front and rear underbody protection, matt silver inlays in the side sills, aluminum-look exterior mirrors, S-specific exhaust system
• LED headlights including high-beam assist as standard, HD Matrix LED headlights as an option
• Spacious lounge-like interior with dark colors
• Optional S sport seats plus with climate control and massage functions, Valcona leather and rhombus pattern
• Rear seats movable along the longitudinal axis as an option, luggage compartment with a volume of up to 1,755 liters (62.0 cu-ft)

Controls and connectivity

• Digital MMI touch response control concept with two displays, natural language voice control with onboard and online information as standard
• Top infotainment system MMI navigation plus with Wi-Fi hotspot and LTE Advanced as standard
• Audi connect with new Car-to-X services such as traffic light information and Amazon Alexa
• Audi virtual cockpit with “S Performance” display as standard, optional head-up display
• Personalization as standard, Audi connect key upon request
• Bang & Olufsen 3D Advanced Sound System and Audi phone box as an option
• Numerous assist systems, including adaptive cruise assist and efficiency assist

The strongest diesel engine in Europe: the 4.0 TDI
With the biturbo V8 that drives the SQ8 TDI (combined fuel consumption in l/100 km: 7.8 (30.2 US mpg); combined CO₂ emissions in g/km*: 205 – 204 (329.9 – 328.3 g/mi)),Audi is presenting the strongest diesel engine on the European market. The eight-cylinder engine combines immense power with a high level of economy and integrates a whole package of high-tech solutions. It provides 320 kW (435 metric hp) and 900 Nm (663.8 lb-ft) of torque between 1,250 and 3,250 rpm. This allows the 4.0 TDI to accelerate the large SUV coupe like a sports car: The Audi SQ8 TDI accelerates from a standstill to 100 km (62.1 mph) in 4.8 seconds; the electronic propulsion limit kicks in at 250 km/h (155.3 mph). In the WLTP cycle, the Audi SQ8 TDI consumes just 7.8 liters (30.2 mpg), which corresponds to 205 – 204 grams of CO₂ per kilometer (329.9 – 328.3 g/mi)*.

* Figures depending on the tires and alloy wheel rims used

In the cylinder heads of the 4.0 TDI that draws its power from 3,956 cm³ of displacement, the intake side is on the outside and the hot exhaust side with the two turbochargers is in the inner “V.” As a result, the gas travel paths are short, which enables spontaneous responding behavior. The turbos, which build up to 2.4 bar of boost pressure (relative) are operated according to the principle of sequential turbocharging: Only one charger is active at low engine speeds; the second charger is activated at 2,200 rpm. To do this, the Audi valvelift system (AVS) opens the second exhaust valve in each of the combustion chambers, which was closed previously.

Fully variable thermal management and sophisticated measures in the crankshaft and camshaft drive systems reduce the friction of the 4.0 TDI, which operates with more than 200 bar of ignition pressure in wide areas of the characteristics map. The common-rail system generates up to 2,500 bar of injection pressure. The sonorous sound of the eight-cylinder engine is amplified by a sound actuator in the exhaust system, which drivers can adjust to their personal preferences via the Audi drive select system. The power of the V8 engine is emphasized by an engine cover specific to the S model series. Red applications flank the striking contours of the cylinder and visualize the air ducting.

Top start-off performance: the electric powered compressor
An electric powered compressor (EPC)supplements the work of the two turbochargers when starting off and when accelerating at a low engine speed. It thereby enables the spontaneous build-up of high torque, ensures homogeneous power delivery and full power for passing.

The EPC operates with a constant voltage of 48 volts. It is situated in the intake air path behind the intercooler and is active in the following two operating statuses: During start-up, the bypass closes and the EPC precompresses the air flow. This increases the filling of the combustion chamber. When driving, if the load requirement from the accelerator is high while the amount of energy available in the exhaust gas is low, the bypass flap closes and the intake air flows into the EPC, where it is compressed for the second time. A compact electric motor with an output of up to 7 kW accelerates the compressor wheel of the EPC to up to 70,000 rpm in approximately 250 milliseconds.

Increasing efficiency: the mild hybrid system
The drive power for the EPC comes from the 48-volt main electrical system of the Audi SQ8 TDI, which is also the backbone of the mild hybrid system (MHEV). A compact lithium-ion battery with an energy capacity of 0.5 kWh serves as its energy storage unit. The second major element of the MHEV system is the belt alternator starter (BAS), which is connected to the crankshaft. During braking, it can recover up to 8 kW of power and feed the energy into the battery. A DC/DC converter connects the 48-volt system and 12-volt electrical system.

The MHEV technology has the potential to reduce real-world fuel consumption by up to 0.5 liters (0.1 US gal) per 100 kilometers (62.1 mi). If the driver lifts off the accelerator at a speed between 55 and 160 km/h (34.2 and 99.4 mph), the Audi SQ8 TDI can, depending on the situation, either recuperate, roll at idle or coast with the engine deactivated for up to 40 seconds. The BAS restarts the engine the next time the accelerator is depressed, and it does so faster or more gently than a conventional starter. Start-stop operation begins at a residual speed of 22 km/h (13.7 mph).

quattro drive with a sport differential as an option: the power transmission
The 4.0 TDI transmits its drive torque to an eight-speed tiptronic. Its two-mass flywheel integrates a torque-adaptive torsional damper that largely compensates the vibrations of the V8 diesel engine which occur just above idle speed. It thereby enables efficient driving in the low revolution range. Detailed solutions such as a clutch in the central transmission and an electric oil pump enable the automatic transmission to work together with the MHEV technology.

As in every S model from Audi, quattro permanent all-wheel drive comes as standard in the SQ8 TDI. In regular driving, it distributes the torque at a ratio of 40:60 between the front and rear axles, creating a sporty, rear-biased driving style. When necessary, the self-locking center differential transfers most of the drive torque to the axle with better traction. Up to 70 percent can flow to the front wheels and up to 85 percent to the rear wheels. At the cornering limit, the wheel-selective torque control rounds off the handling with minor brake interventions at the relieved wheels on the inside of the curve.

The sport differential, which Audi offers in the advanced suspension package, is the ideal addition to the quattro drive. It distributes the drive torque actively between the rear wheels. When turning or accelerating in a curve, they are predominantly steered toward the wheel on the outside of the curve—the Audi SQ8 TDI is literally pressed into the curve, eliminating even the slightest hint of understeer. In case of oversteer, the sport differential stabilizes the large SUV coupe by shifting torque to the wheel on the inside of the curve.

Dynamics as standard: progressive steering, sport air suspension, Audi drive select
As the sporty top model of the Q8 family, the Audi SQ8 TDI offers outstanding vehicle dynamics. It is quick to respond in tight curves, confident on the highway and robust off road. As standard, the large SUV coupe is equipped with progressive steering that responds spontaneously and works with a high level of precision. It features a sporty ratio of 14.6:1 in the center position and becomes even more direct with increasing steering angle.

Another important standard feature is the adaptive air suspension sport air suspension with adjustable damping. It changes the level position of the body depending on the speed and according to the driver’s request: There is a difference of 90 millimeters (3.5 in) between the raised level for off-road driving and the low level for driving on the highway.

The adjustment is performed via the standard dynamic handling system Audi drive select, which influences the air suspension as well as the function of other drive and suspension components and thereby changes the character of the SQ8 TDI. The driver can vary between seven profiles here: auto, comfort, dynamic, individual, efficiency, allroad, and offroad. In the last two modes, the ground clearance of the Audi SQ8 TDI is increased by 15 mm (0.6 in) compared with the normal level. The driver can use the “raise” function to increase the ground clearance by an additional 35 millimeters (1.4 in) to a maximum of 254 millimeters (10.0 in) up to a speed of 30 km/h (18.6 mph). As the speed increases, the suspension automatically lowers the body gradually. This results in a reduction of aerodynamic drag and increased vehicle dynamics.

If the driver chooses offroad mode in Audi drive select, the electronic stabilization control automatically switches to stability, traction and braking control modes that are optimized for off-road driving. The standard hill descent control system is also activated. It provides support by means of automatic brake interventions when driving down a steep gradient that exceeds six percent. The electronic chassis platform captures the tilt angle of the car and displays this information for the driver on the MMI. Due to the specific design of the front and rear end, the angles of approach/departure of the Audi SQ8 TDI are even larger than those of the Audi Q8: 23.2 degrees at the front and 24.3 degrees at the rear at off-road level.

Five-link suspensions are used at the front and rear axles of the SQ8 TDI so that longitudinal and lateral forces can be handled separately. The linkages and the subframes are made largely of aluminum. The SUV coupe has a track width of 1,679 millimeters (5.51 ft) up front and 1,687 millimeters (5.53 ft) at the rear. 21-inch cast aluminum wheels with 285/45 tires are mounted as standard. Audi and Audi Sport deliver 22-inch wheels with a 285/40 tire format as an option. Powerful six-piston fixed-caliper brakes work at the front axle; the internally ventilated gray cast iron brake disks have a diameter of 400 millimeters (15.7 in) here. The diameter at the rear axle is 350 millimeters (13.8 in). Upon request, Audi will install red brake calipers or carbon fiber ceramic disks, which are lighter and more abrasion‑resistant than steel disks.

High-tech systems: all-wheel steering and roll stabilization
Audi offers all-wheel steering in the advanced suspension package or individually; it operates at the rear axle with a spindle drive and two tie rods. At low speeds, for example during maneuvering and parking operations, it turns the rear wheels in the opposite direction to increase agility and reduce the turning radius. It reaches its maximum angle of 5 degrees at around 5 km/h (3.1 mph). At driving speeds upwards of 60 km/h (37.3 mph), it is the opposite: The rear wheels then turn slightly in the same direction. This improves the steering response and further increases stability when changing course at higher speeds.

The third high-tech system of the advanced suspension package, along with all-wheel steering and the sport differential, is the electromechanical active roll stabilization. There is a compact electric motor that generates up to 3 kW of power between each of the two halves of the stabilizer on each axle. When driving straight ahead, the suspension control ensures that both halves of the stabilizer act largely independently of one another. This reduces the sprung mass vibrations on uneven roads and thereby increases ride comfort. At sporty paces, however, the focus is on optimum roll compensation. The halves of the stabilizer act as a unit and are twisted in opposite directions by the transmission of the electric motor; the roll angle is reduced significantly when cornering, and the handling of the SQ8 TDI becomes even more firm and dynamic. The electromechanical active roll stabilization draws its power from the powerful 48-volt main electrical subsystem. Using the forces of the stabilizers as a basis, the electric motors can generate power and thus feed power back to the battery.

Management of all adjustable suspension systems is integrated into the control unit for the electronic chassis platform (ECP). As the central suspension controller, it collects all key data about the movement of the car and about the systems involved. The integral dynamic handling controller then uses these data to compute the optimal function of these components.