Review: Audi D4 S8 (2014-on)

Overview

Released in Australia in May 2014, the Audi D4 Series II (D4.II) S8 was a high-performance, luxury sedan. Manufactured in Neckarsulm, Germany, the Audi D4 S8 was powered by a 4.0-litre twin-turbo V8 petrol engine that was mated to an eight-speed ZF 8HP automatic transmission and drove all four wheels via Audi’s quattro system.

4.0 TFSI V8 engine

Based on the V10 engine from the Audi C6 RS6 , the 4.0-litre twin-turbo V8 CGTA engine had direct injection (Audi’s ‘Fuel Stratified Injection’ or FSI), double overhead camshafts per cylinder bank, two twin-scroll turbochargers, air and water intercoolers, continuously variable valve timing for the intake and exhaust camshafts, four valves per cylinder and a compression ratio of 10.5:1. Other features of the engine included:

• A ‘cylinder on demand’ cylinder management system which could deactivate four cylinders under part load throttle applications. When in operation, an Active Noise Cancellation (ANC) system was activated and used four microphones – integrated into the vehicle’s headlining – to produce anti-phase sounds through the vehicle’s sound system;
• An ‘idle stop’ system which enabled the engine to shut down when the vehicle was stationary to conserve fuel;
• A brake energy regeneration system which regulated alternator output to recharge the battery when the vehicle was braking or coasting; and,
• Engine noise minimisation devices such as electronically-controlled bearings, a sound actuator, flaps in the exhaust system and a newly developed two-mass flywheel with a centrifugal force pendulum in the transmission.

The D4 S8 could accelerate from rest to 100 km/h in 4.2 seconds and had an electronically-limited top speed of 250 km/h. Furthermore, fuel consumption for the combined ADR 81/02 test cycle was 9.6 litres per 100 km.

quattro and torque vectoring

The Audi S8’s quattro four-wheel drive system utilised a ‘Crown Gear’ centre differential. In normal conditions, the system will provided a 40:60 front:rear torque split. If a loss of traction was experienced, however, up to 85 per cent of the engine’s torque could be directed to the rear axle, and up to 70 per cent to the front axle. The system also included open front and rear differentials with electronic differential locks which could brake spinning wheels to enable cross-axle torque transfers.

The Audi S8 also had a ‘torque vectoring’ rear axle which could selectively distribute torque between the rear wheels to generate yaw and thereby correct over- or under-steer.

Dimensions and body

Compared to the Audi D3 S8 , the Audi D4 S8 was 80 mm longer (at 5131 mm), 54 mm wider (1948 mm), 17 mm taller (1461 mm) and had a 48 mm longer wheelbase (2992 mm); kerb weight was 1975 kg. Like its predecessor, the D4 S8 had an aluminium monocoque with only the B-pillars made of ultra high-strength steel. Due to the use of higher-strength body components, static torsional rigidity for the D4 S8 was 25 per cent greater than its predecessor.

Suspension

Like the Audi D4 A8 on which it was based, the D4 S8 had five link front suspension with two transverse links on the upper plane, the support link and control arm in the lower plane and a track rod. Furthermore, the independent rear suspension had track-controlled, hollow-cast trapezoidal links with the struts resting directly on the wheel carriers. The S8 was also equipped with adaptive air suspension and variable dampers, enabling the driver to select from three ride heights.

Safety equipment

Standard safety features for the Audi D4 S8 included dual front airbags, side airbags for front and rear occupants, full-length curtain airbags (i.e. for front and rear occupants), ABS, electronic brake force distribution, brake assist, electronic stability control, traction control, active front seat head restraints and front seatbelts with pretensioners and load limiters.

The S8 was also equipped with Audi’s ‘pre-sense’ system – which prepared the vehicle for imminent collisions – and ‘active lane assist’ system which would make slight steering adjustments when necessary to keep the vehicle in its lane.

Brakes

The Audi S8 had internally ventilated front and rear brake discs, measuring 400 mm (diameter) at the front and 365 mm at the rear.

Features

Standard features for the Audi D4 S8 included 21-inch alloy wheels, Audi’s Multi Media Interface (‘MMI’) with satellite navigation, an eight-inch high resolution display, DVD player, digital TV tuner, Bluetooth connectivity and voice recognition, a 600 watt Bose surround sound system with fourteen speakers and a 12 channel amplifier, a digital radio receiver (DAB+), CD player and auxiliary inputs (iPod/USB/MP3), an in-car Wi-Fi hotspot (‘Audi Connect’), four-zone climate control air conditioning, Valcona leather upholstery, 22-way power adjustable front seats with ventilation, heating and massage functions, cruise control, head-up display, LED headlights, daytime LED running lights, front and rear parking sensors, a reversing camera, a leather-wrapped steering wheel with gearshift paddles, remote central locking with proximity key, power windows, power adjustable and heated door mirrors with folding function, a power adjustable steering column (height and reach), driver memory settings (for the seat, door mirrors and steering wheel), a glass power-operated sunroof, Alcantara headlining, an electrochromatic rear view mirror, ambient lighting, a power-operated boot lid and servo closing doors, an electrochromatic rear view mirror, tyre pressure monitoring, an alarm and immobiliser.

The S8 was also equipped with Audi’s ‘Park assist’ function which used twelve ultrasonic sensors to provide a 360 degree display of the vehicle and could autonomously steer the vehicle into parallel and perpendicular parking spaces.

Audi S8 Plus

Commencing production in September 2015 and officially released in Australia in April 2016, the Audi S8 Plus was powered by the DDT engine which produced peak outputs of 445 kW and 750 Nm. As a result, the S8 Plus could accelerate from rest to 100 km/h in 3.8 seconds.

The Audi S8 Plus could be identified by its 21-inch ‘Audi Sport’ alloy wheels in matt titanium look, carbon front centre blade and rear diffuser with carbon surrounds, high-gloss black exterior package, body-colour door mirror housings and sport exhaust system with quad high-gloss black tail pipes.

Inside, the Audi S8 Plus was further equipped with:

• The full leather package which included the upper dashboard, upper door trim and seat backrest covers;
• The extended leather package which included the lower door trims, lower dashboard and glove box lid; and,
• An Alcantara headlining

Related links

• Specifications: Audi D4.II S8 (May 2014)
• Specifications: Audi D4.II S8 and S8 Plus (April 2016)
• Audi Australia: Audi S8
• Wikipedia.org: Audi D4 S8