Audi's exterior design and new ideas for electrification

    At the 2014 Los Angeles Auto Show, Audi showcased its new design ideas for exterior design and electric drive assembly through two concept cars.

    The Prologue concept car previews the exterior design of Audi's full-size luxury coupe. The future production version will be positioned higher than the A8 and may be called the A9. The Prologue concept car is 5100 mm long, slightly shorter than the A8. Its exterior style is not limited to a new car, but may also be extended to many future Audi small cars. To quote Audi design director Andreas Mindt: "This car reveals the future."

    Specifically, the Prologue's wide hexagonal grille will become a new feature of Audi sedans. Meanwhile, the SUV will have an octagonal grille. The Prologue's clean lines not only retain the Audi brand's recognition, but also make it more trendy. "The Audi brand is focused on design and must continue to evolve," Mindt said.

    Prologue's wheels are 22 inches, which is common on concept cars. It uses unique laser headlights. Lasers are convergent, and if they are shot directly at the road, they can only illuminate a small bright spot. So the laser first shoots at the lens, which disperses the laser to the entire road. In addition, there are five small lenses with optical fibers to change the direction of the light to adapt to road conditions. Unlike many current Audi models that use all-aluminum bodies, Prologue uses both aluminum and high-strength steel to improve collision safety in key locations.

    At the rear, the LED taillights continue the current Audi design language, but emphasize the Prologue's width. When the taillights are on, the large number of lines in the lampshade give the illusion that the taillights are gradually moving backwards towards the viewer. Audi has used a lot of innovative technology in the cockpit of the Prologue. When the user gets in the car, the vehicle will automatically recognize the driver's identity through the mobile phone pairing, and adjust the seat and air conditioning to the user's preferred settings.

    The interior is composed of three touch-sensitive LED screens that span the entire panel. Two of the screens are located in front of the driver, the left screen is a digital instrument that can also set the headlights and driving assistance system, and the right screen is used to control media functions.

    The third screen is located in front of the co-pilot, which can independently control the entertainment functions. The co-pilot can also operate the navigation system on this screen, and with a swipe of the finger, the navigation information can be dragged to the screen on the driver's side. The Prologue also has a high-pixel OLED display located in the center console, which is responsible for controlling the air conditioning and handwriting input.

Power and Control

    Prologue also innovatively uses four-wheel steering. Although users are not keen on four-wheel steering, Audi believes that the time is ripe. Ulrich Hackenberg, member of the Volkswagen Group's board of directors responsible for technical development, said: "Four-wheel steering will become a typical configuration for premium cars."

    When maneuvering at low speeds, the rear wheels can turn in the opposite direction of the front wheels, up to five degrees. At high speeds, the rear wheels turn in the same direction as the front wheels, improving driving stability. The Prologue is equipped with a 4.0-liter turbocharged engine with a maximum power of 597 horsepower and a maximum torque of 750 Nm. The eight-speed Tiptronic automatic transmission is responsible for transmission, and the four-wheel drive uses Audi quattro technology. The Prologue also has a 48-volt mild hybrid system. The electrical energy comes from brake recuperation, with a maximum recuperation power of 12 kilowatts. Audi will equip a mass-produced model with this mild hybrid system in the near future.

    Another concept car looks the same as the regular A7, but has two powertrains: fuel cell and lithium-ion battery/plug-in hybrid. Audi has not given up on developing fuel cell technology because battery technology is progressing slowly. Hackenberg said: "At present, fuel cells are the better solution, but the performance of lithium-ion batteries is still improving, so we can't say which one will win." After weighing the pros and cons, Audi combined the two powertrains on this A7 Sportback h-tron, with the fuel cell taking the lead, driving the front and rear electric motors, and four-wheel drive.

    It has a total power of 170 kW, a total torque of 540 Nm, a weight of 1,950 kg, an acceleration of 7.9 seconds from 0 to 100 km/h, and a top speed of 180 km/h. It has a range of 500 km after being fully refueled with hydrogen fuel, and refueling takes only three minutes, both of which lithium-ion electric vehicles cannot do.

    The fuel cell has a driving efficiency of 60%, which is twice that of an internal combustion engine. It consumes one kilogram of hydrogen per 100 kilometers, which is equivalent to 62mpg. Audi promises that the fuel cell can work at a minimum of minus 28 degrees. The outer shell of the hydrogen fuel tank is made of carbon fiber composite material, and the inner layer is made of aluminum. It is located under the trunk and can store five kilograms of liquid hydrogen at a storage pressure of 700 bar.

    With the electric drive system, it is easier to arrange the brake energy recovery device. Engineers took the 8.8 kWh lithium-ion battery pack from the A3 Sportback e-tron and installed it in the A7 h-tron. This battery alone can sustain the A7 h-tron for 50 kilometers. Using a 230-volt socket, it takes four hours to charge.

    Hackenberg stressed that the hydrogen fuel cell of the A7 h-tron has been perfected and can be mass-produced, but the lack of infrastructure has limited its promotion. He said: "The first markets to launch hydrogen fuel cell vehicles must have sufficient infrastructure. At present, California in the United States is second to none, and Germany is second, not far behind California."