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Audi A8 hybrid

Audi A8 hybrid with 2 litre four-cylinder TFSI petrol engine and electric motor

The Audi A8 hybrid has been confirmed for production, and it will combine outputs of 245PS and 480Nm with sub-148g/km CO 2
.

This will be the result of a 2.0-litre four-cylinder TFSI petrol engine, an electric motor, and a lithium-ion battery, which will mean emissions-free running at speeds of up to 62 mph, as well as fuel economy in excess of 44 mpg.

Audi’s flagship model has been designed as a parallel hybrid. Its 2.0-litre TFSI engine, which has been modified in some areas, generates an output of 211PS and makes a 350 Nm torque peak available between 1,500 and 4,200 rpm. The combustion engine works together with an electric motor which generates 40 kW (54 PS) and 210 Nm.

The permanent magnet synchronous motor is mounted in the space usually occupied by the torque converter in front of the modified eight-speed tiptronic transmission. A multi-plate clutch connects or disconnects the electric motor and the TFSI engine. The smooth and fast-shifting hybrid transmission transmits the torque to the front wheels.

According to the provisional figures generated by early-stage tests, the Audi A8 hybrid will be capable of reaching 62 mph from rest in 7.7 seconds and continuing to a top speed of 146 mph, while returning in excess of 44 mpg in the EU combined cycle test, along with CO 2
emissions of less than 148 g/km.

The Audi A8 hybrid can drive at up to 62 mph purely on electric power and it has a range of up to 1.86 miles at a constant 37 mph.

The driver has the choice of three modes: The ‘EV’ setting gives priority to the electric drive, while the ‘D’ option efficiently controls both the engine and the electric motor. The ‘S’ mode and the tiptronic gate place the emphasis on optimal acceleration.

A hybrid saloon with 5 operating states

Audi’s hybrid saloon has five operating states: with the TFSI engine alone, with electric drive only or in hybrid mode; recuperation and boosting are also possible. Two displays show the driver all operating modes in detail.

The lithium-ion battery, which weighs 36.7 kilograms, is located in a crash-proof area in the boot. It provides 1.3 kWh of nominal energy and up to 40 kW of power. Two different methods are used to air-cool the battery, depending on need: air is either blown from the passenger compartment by a fan or via a separate cooling circuit coupled to the automatic air conditioning system. The battery is thus kept within the temperature window required for it to perform to its full potential. The electric motor and the compact power electronics which serve as a controller between the electric motor and the battery are water-cooled.

In visual terms, the Audi A8 hybrid is distinguishable by details such as its 18-inch or optional 19-inch ten spoke alloy wheels which resemble turbine blades; hybrid badges; and an exclusive Arctic Silver paint finish. The metallic paint finish is a standard feature, as are three-zone automatic air conditioning, LED headlights and a BOSE sound system.

The Audi A8 hybrid will be one of the lightest saloons in its category. Its ASF (Audi Space Frame) body is made almost entirely of aluminium, with ultra-high-strength steel used only for the B-pillars to optimise rigidity. Weighing just 231 kilograms, it is roughly 40 per cent lighter than a comparable steel construction.

Series production of the will begin in 2012, and it will reach the UK late next year.

Read our road test of the new Audi A6 2.0 TDI