Just water will be left behind your superfast Audi A7
The A7 Sportback h-tron quattro, which Audi is unveiling at the Los Angeles Auto Show 2014, uses a powerful, sporty electric drive with a fuel cell as its energy source that operates in combination with a hybrid battery and an additional electric motor in the rear. The overall electrical system power of 170 kW is transferred to both the front and the rear wheels. This drive configuration makes the emission-free Audi A7 Sportback a quattro through and through – a new departure in fuel cell cars.
The crucial differences are beneath the hood of the A7 Sportback: The fuel cell in the Audi technology demonstrator is installed at the front, mirroring the conventional A7 Sportback with combustion engine. Because the exhaust system only has to handle water vapor, it is made of weight-saving plastic. The fuel cell itself comprises over 300 individual cells that together form a stack. The core of each of these individual cells is a polymer membrane. There is a platinum-based catalyst on both sides of the membrane.
The silent propulsion is fully available from the off, and the fuel cell reaches its maximum output within one second at full load, a more dynamic response than a combustion engine because the entire drive system involves only a few mechanical components.
With 540 Nm (398.3 lb-ft) of propulsive power at its disposal the Audi A7 Sportback h-tron quattro, which tips the scales at only around 1,950 kilograms (4,299.0 lb), races from a standstill to 100 km/h (62.1 mph) in 7.9 seconds. Its top speed is 180 km/h (111.8 mph), a top figure for its field of competitors. The e-quattro concept requires precise coordination of the electric motors, the technology demonstrator offers a sporty, stable and high-traction drive that is comparable to a production car with mechanical quattro drive.
Switching from automatic transmission mode D to S increases the level of energy recovery when braking, so that the battery is charged up effectively during sporty driving. Brake applications, too, are almost always accomplished fully electrically: The electric motors then act as alternators and convert the car's kinetic energy into electrical energy that is stored in the battery. The four disk brakes only become involved if more forceful or emergency braking is required.
The four hydrogen tanks of the Audi A7 Sportback h-tron quattro are located beneath the base of the trunk, in front of the rear axle, in the center tunnel. The tanks can store around five kilograms of hydrogen at a pressure of 700 bar, enough to drive over 500 kilometers (310.7 mi). According to the NEDC cycle, fuel consumption is roughly one kilogram (2.2 lb) of hydrogen per 100 kilometers (62.1 mi), an amount with an energy content equivalent to 3.7 liters (1.0 US gal) of gasoline. ■
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