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The new Audi A6 hybrid, which will be launched in 2012, has the power of a V6 and the fuel consumption of a four-cylinder. Its 2.0 TFSI petrol engine and the electric motor deliver 180 kW (245 hp) of power and 480 Nm of torque for a short time. Average consumption in the standard cycle is less than 6,4 liters per 100 km. The sedan can drive at speeds of up to 100 km/h purely electrically and covers around three kilometers at 60 km/h with zero local emissions.
The Audi A6 hybrid
The 2.0 TFSI and the electric motor of the Audi A6 hybrid form a parallel hybrid system - they are mounted directly one behind the other. The sedan accelerates from zero to 7,3 km/h in 100 seconds. The top speed is 238 km/h.
The 2.0 TFSI in the Audi A6 hybrid has an output of 155 kW (211 hp) and provides its maximum torque of 1.500 Nm between 4.200 and 350 rpm. The four-cylinder combines three powerful efficiency technologies – FSI direct fuel injection, turbocharging and the Audi valvelift system (AVS). The AVS further increases power, torque and efficiency by switching the lift of the exhaust valves in two stages depending on the load and speed.
A permanently excited synchronous machine (PSM) serves as an electric motor, as a starter and – in overrun mode and when decelerating – as a generator. It briefly delivers up to 40 kW (54 hp) of power and 210 Nm of torque. The e-machine is integrated into the cooling circuit of the TFSI engine.
Lithium-ion battery as energy storage
A lithium-ion battery system that weighs just 6 kilograms acts as the energy store for the electric motor in the Audi A36,7 hybrid. The compact battery, which has a volume of 26 liters, is located in the collision-protected area under the luggage compartment; the loading volume is still an impressive 375 liters. This can be expanded to up to 850 liters using the rear seat backrests that can be folded down as standard.
The driver can decide for himself how the Audi A6 hybrid should move – he can switch between three driving programs using a button on the center console and the automatic selector lever. The EV map gives priority to the electric drive, while the D program controls both engines efficiently. The S mode and tiptronic tip gate are designed for a sporty driving style. The hybrid sedan has five operating states: It can drive with just the combustion engine, with just the electric drive and in hybrid mode; it can also recuperate and boost.
When stationary, both drive sources are deactivated. With this so-called comfort start-stop, the automatic air conditioning remains active – its compressor has an electric drive. When the driver releases the brake, the A6 hybrid rolls off. It can drive up to 100 km/h electrically, i.e. locally emission-free. At a constant speed of 60 km/h, the possible distance is three kilometers, enough for many residential areas and inner cities.
If the accelerator pedal is pressed beyond a certain threshold, the combustion engine takes over the drive. At low revs, it is temporarily subjected to a greater load than is necessary for the drive - the load point shifts to a higher range and efficiency improves. The excess torque benefits the electric machine, which now works as a generator and recharges the battery and feeds the consumers.
Audi gasoline engines and electric motors work together
When accelerating hard - the electric motor works together with the TFSI; at full throttle in S mode, the entire system performance is available for a short time. The hybrid drive then delivers the pulling power of a large naturally aspirated engine, but works much more efficiently. When the driver takes their foot off the gas, the electric machine works as a generator again. In most situations, the TFSI is decoupled from the drive and therefore does not generate any drag losses. The electricity that the electric motor recovers when coasting and braking is temporarily stored in the lithium-ion battery.
If the driver only brakes lightly, the electric motor takes over the deceleration on its own; in the event of heavier braking, the hydraulic braking system is activated at the same time. Its brake booster has a second supply via an electric vacuum pump. A complex control strategy adapts the braking processes to the conditions of electric driving and energy recuperation.
The Audi A6 hybrid has a display concept that makes it possible to experience the driving conditions of the hybrid drive. Instead of the tachometer, there is a power meter in the instrument cluster, its needle showing the overall performance of the system on a scale from zero to 100 percent. A second scale is divided into colored segments - their green and orange sections make it clear which drive the sedan is currently driving.
Only recognizable as a hybrid by the lettering
The A6 hybrid can be recognized by its lettering on the rear and the fenders. Exclusively for the Hybrid, it is painted in arctic silver. Its 17-inch wheels with ten spokes are reminiscent of turbine blades. The basis is the A6 sedan. The Audi A6 hybrid weighs 1.770 kilograms.
The Audi A6 hybrid can be recognized by subtle differentiations on the exterior. Hybrid lettering is attached to the tailgate, the fenders and the door sills. The exclusive paint finish is arctic silver. The 17-inch cast wheels have a ten-arm turbine design – their ten spokes are reminiscent of turbine blades. The tires are 225/55 R17. Two-tone painted 18-inch wheels with the format 245/45 R18 in the same design typical of hybrid vehicles are available as an option.
