Audi S5 gains TDI power, 48 volts and an EPC

Audi S5

For the first time in its history, the Audi S5 now has a V6 diesel at its heart. Underpinned by mild hybrid technology, it equips the peak performer with impressive staying power between fill-ups and delivers even greater immediacy of response courtesy of an electric powered compressor.

The 3.0 TDI engine, which will be introduced in both the S5 Coupé and the S5 Sportback in late 2019, now produces 347PS and delivers up to 700 Nm (516.3 lb-ft) of torque to the crankshaft, available between 2,500 and 3,100 rpm. This combination of power, torque and efficiency sets the S5 apart in this segment.

The 3.0 TDI in the S5 models is the most powerful version in the Audi V6 diesel engine line-up. Both the electric powered compressor (EPC) and mild hybrid (MHEV) systems are embedded in the standard 48-volt main electrical circuit. For the first time in the S5 TDI, a powerful 48–volt belt alternator starter is the heart of the mild hybrid system with maximum recuperation power of up to 8 kW. A DC/DC converter steps this voltage down for components in the 12–volt electrical system. A compact, air-cooled lithium-ion battery with a capacity of 0.5 kWh installed under the luggage compartment floor serves as the energy centre.

With these characteristics, the V6 diesel engine is the ideal power plant for agility, spontaneity, low fuel consumption and long range, with a suitably resonant sound to match.

Acceleration to 62mph in the S5 Coupé takes 4.8 seconds and and 4.9 seconds in the S5 Sportback, with both reaching their peak at an electronically limited 155mph.

The electric powered compressor in the Audi S5 TDI is new to this segment. It is located in a bypass downstream of the intercooler and thus close to the engine. From the outside, the compressor looks similar to a conventional turbocharger. A compact electric motor replaces the turbine wheel, however. With an output of up to 7 kW, it accelerates the compressor wheel to 65,000 rpm in approximately 300 milliseconds. It is activated whenever the power demand from the driver is high but the energy available in the exhaust flow for driving the compressor wheel is low. If this is the case, the bypass valve closes and directs the intake air to the EPC. The compressed air flows directly into the combustion chamber. This enables the driver to tap the full power of the 3.0 TDI instantly even at low engine speeds, whether passing another vehicle or accelerating out of a corner. Because the technology increases torque at the lower end of the rpm range, it provides for lower engine speeds and less frequent downshifts during relaxed driving. From a standing start, the new S models quickly move several metres ahead of comparable vehicles without an EPC.

The mild hybrid system in the S models, which is also integrated into the new 48-volt electrical system, has the potential to reduce customer fuel consumption by as much as 0.4 litres per 100 kilometres. Mounted on the end face of the 3.0 TDI is a water-cooled belt alternator starter (BAS), which is connected to the crankshaft via a particularly high-load poly-V belt. The BAS generates a recuperation power of up to 8 kW and 60 Nm (44.3 lb-ft) of torque.

It interacts closely with the TDI engine, which in many situations can be operated more closely to its ideal load point as a result. That enhances efficiency.

When drivers take their foot off the accelerator pedal at a speed between 34 and 99mph, the car can coast for up to 40 seconds with the engine shut off completely. The lithium-ion battery continues to supply electricity.

The engine management system decides in every situation whether coasting, freewheeling or recuperation, i.e. the recovery of kinetic energy, is most efficient. It does this using information from the navigation system and the onboard sensors. The energy recovered by the BAS during coasting and braking flows into the 48-volt storage unit or directly to the electrical consumers.

The mild hybrid system not only reduces fuel consumption; it also provides greater comfort and convenience. The conventional starter is only used to start the car initially, when cold engine oil requires high forces. When the driver presses the accelerator pedal again after a coasting phase or a stop, the BAS restarts the combustion engine. The system does this as required by the driver’s wishes and the situation, from very smoothly to very quickly. Start-stop operation begins at 13mph. When stopped, the engine restarts as soon as the car in front starts to move, even if the brake is depressed.

The wide, low Singleframe grille features three-dimensional aluminium struts and is flanked by the standard LED headlights. The front bumper is strongly three-dimensional and richly contoured. U-shaped clasps structure the large, pentagonal air inlets, which are partly filled with honeycomb grilles. Separate openings on their outer edge direct a portion of the airflow into the wheel housings, where it flows past the wheels for improved aerodynamics. A horizontal, aluminium-look blade in the bumper forms the lower edge of the nose.

When viewed from the side, the exterior mirrors with their aluminium-look housings and the strongly contoured side sills are particularly eye-catching. The S5 Coupé and the S5 Sportback have a spoiler integrated into the luggage compartment lid. LED rear lights with dynamic turn signals are standard. A flat honeycomb grille is integrated into the rear bumper, while a diffuser insert in titanium black matt frames the two dual chrome tailpipes of the exhaust system.

Inside, the seat coverings – optionally with contrast stitching – are available in either a leather/Alcantara combination or the top grade Fine Nappa leather. Buyers can choose from the colours black, rotor grey and magma red.

Sport seats with an embossed S logo are standard. Strongly contoured super sport seats with integrated head restraints, rhombus pattern and massage function are optionally available. The MMI display displays a welcome screen with an S5 logo when the ignition is switched on. Illuminated door sill strips, the sport leather steering wheel with multifunction plus and the clasp on the tiptronic selector lever bear the S logo with a red rhombus. The pedal caps and the footrest are stainless steel; the inlays are made of matt brushed aluminium or optionally carbon Atlas.

The MMI system on board the S5 models offers a highly modern control logic. With its flat hierarchies, it is oriented on modern smartphones, including the intelligent free-text search function.

The voice control function recognises inputs from everyday speech. Audi virtual cockpit fitted as standard also presents all key information on its 12.3-inch display. One of the three views from which the driver can choose is the S mode, in which the tachometer takes centre stage. The optional head-up display projects important data onto the windscreen as symbols and digits.

The infotainment system for the S models is modular, with MMI navigation plus with MMI touch and an 8.3-inch monitor topping the infotainment range. The rotary pushbutton has a touchpad for zooming, scrolling and entering characters. The system includes the Audi connect hardware module, which connects the car to the internet via LTE and also includes a Wi-Fi hotspot. It also delivers the numerous Audi connect internet services to the car, ranging from traffic information online to remote functions. The free myAudi app connects a smartphone with the car.

The optional Audi phone box connects smartphones to the on-board antenna by near-field coupling and charges them inductively using the Qi standard. Particularly discerning hi-fi fans can choose the Bang & Olufsen Sound System with 3D sound. The Audi smartphone interface brings Apple CarPlay and Android Auto on board for iOS and Android phones, respectively.

The electric powered compressor in the Audi S5 TDI is new to this segment. It is
located in a bypass downstream of the intercooler and thus close to the engine. From
the outside, the compressor looks similar to a conventional turbocharger. A compact
electric motor replaces the turbine wheel, however. The efficiency of a 48V PMAC
motor is the first consideration in today’s energy-conscious world.

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