Audi S5 Sportback g-tron. Click to enlarge.

The A5 g-tron is powered by a 2.0 TFSI engine. It develops 125 kW (170 hp) of power and 270 N·m (199 lb-ft) of torque. With CO₂ emissions of just 100 grams per kilometer (160.9 g/mi) (with S tronic), Audi is the first premium manufacturer to offer a gasoline engine in the B segment that achieves lower emissions than a comparable diesel engine.

The newly developed engine is based on the gasoline-powered 2.0 TFSI. The innovative combustion process features a shortened compression stroke and a long power stroke as well as an increased compression ratio that has been specially designed for part load operation—by far the most common operating mode. The intake valves close much sooner than usual. In combination with increased pressure in the intake manifold, this reduces throttle losses during intake.

The tanks for the gas fuel in the A5 Sportback g-tron are located beneath the rearward structure. They store 19 kilograms (41.9 lb) of gas at a pressure of 200 bar and are of an extra-lightweight design. The inner layer consists of a gas-impermeable polyamide matrix, while a second composite layer of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) gives the tank its extremely high strength. The third glass fiber layer helps to visualize any external effects. Epoxy resin is used to bind the fiber reinforced materials.

In the standard driving cycle the A5 Sportback g-tron uses less than four kilograms (8.8 lb) of gas per 100 kilometers (62.1 miles). The customer benefits from extremely low fuel costs. In the NEDC cycle, the bivalent g-tron model running on natural gas covers up to 500 kilometers (310.7 miles). When the pressure in the tank falls below 10 bar with about 0.6 kilogram (1.3 lb) of gas remaining, the engine management automatically switches to gasoline operation. This makes an extra range of 450 kilometers (279.6 miles) available.

The drive unit’s high efficiency means low costs of ownership. Compared with an equivalent gasoline engine, fuel costs are markedly lower, and the reduced CO₂ emissions place the vehicle in a more attractive tax bracket.

Audi e-gas
Audi e-gas is generally produced in two key process steps: electrolysis and methanation. In the first step, renewably generated electricity is used to split water into hydrogen and oxygen. In the second step, the hydrogen is reacted with CO2 to yield synthetic methane.
In the Audi e-gas plant in Werlte in the German state of Lower Saxony, this is done using a chemical-catalytic process under high pressure and high temperature.
In a new process announced earlier this year, methanation is purely biological. Microorganisms absorb the hydrogen that is dissolved in liquid and the carbon dioxide through their cell walls. From these molecules they then form the new molecule methane.
The process is run under a moderate pressure of around five bar and at relatively low temperatures.

The new Audi A5 Sportback g-tron is not only remarkably economical to run, it is also exceptionally clean. Nor does driving enjoyment draw the short straw. In conjunction with the S tronic transmission, the A5 Sportback g-tron accelerates from a standstill to 100 km/h (62.1 mph) in just 8.5 seconds.

The A5 Sportback g-tron is especially eco-friendly when running on Audi e‑gas. This is a first for virtually CO₂-neutral long-distance mobility. Audi produces the fuel at several power-to-gas facilities using renewable energy, water and CO₂. This method enables the brand with the four rings to transform surplus renewable energy into a storable product.

At the same time, Audi is determinedly continuing its research into e-fuels. Together with venture partners, the company has now come up with a new method of producing e-gas. This will assure future supplies for the growing number of g-tron models in circulation. In the new technique, Audi e-gas is obtained by biological methanation involving microorganisms. Compared with the previous chemical process, the gas is now produced at a much lower ambient pressure and at lower temperatures.

The A5/S5 Sportbacks. Customers can choose between two TFSI and three TDI engine versions for the new Audi A5 Sportback. They produce between 140 kW (190 hp) and 210 kW (286 hp) of power. Compared with the previous model, Audi has reduced their fuel consumption by as much as 22% while increasing power output by up to 17%.

The Sportbacks offer a choice of six-speed manual transmission, seven-speed S tronic dual-clutch transmission or eight-speed tiptronic. Front-wheel drive is standard, with quattro all-wheel drive available as an option in two versions. It is standard for the 3.0 TDI with 210 kW (286 hp).

The body of the new Audi A5 Sportback is the lightest in the segment. An intelligent mix of materials makes it 15 kilograms (33.1 lb) lighter than that of the predecessor. The overall weight of the new generation has fallen by as much as 85 kilograms (187.4 lb) to just 1,470 kilograms (3,240.8 lb), excluding the driver.

Suspension. The track width is 1,587 millimeters (62.5 in) at the front and 1,568 millimeters (61.7 in) at the rear. The wheelbase measures 2,824 millimeters (111.2 in).

The front axle features redesigned five-link suspension, while a five-link construction replaces the trapezoidal-link rear suspension used previously. The adaptive dampers available optionally are integrated into the standard Audi drive select dynamic handling system. They make for a driving experience that is both dynamic and comfortable. The new electromechanical power steering provides better road feedback and steering precision. Optionally available is dynamic steering, which varies its gear ratio depending on the speed and steering angle.

Driver assistance systems. The driver assistance systems cover a wide range of functions in the new Audi A5 Sportback. An intelligent combination of different technologies enhances safety, comfort and efficiency. Meanwhile Audi is also taking the next step toward piloted driving.

Playing a central role here is the adaptive cruise control (ACC) Stop&Go system including traffic jam assist. It relieves drivers in slow-moving traffic up to a driving speed of 65 km/h (40.4 mph) by assuming the tasks of braking and accelerating the car, and it also temporarily takes charge of steering it on better roads. The predictive efficiency assistant, which evaluates GPS information from the car’s immediate surroundings, helps to save fuel by giving specific driving advice—a unique feature in this segment.

Collision avoidance assist intervenes if the car needs to drive around an obstacle to avoid an accident. Based on data from the front camera, ACC and radar sensors, it computes a recommended driving line within a fraction of a second. The lineup is rounded out by other assistance systems such as turn assist, park assist, cross traffic assist rear, exit warning, camera-based traffic sign recognition, Audi active lane assist and Audi side assist.

The new Audi A5 and S5 Sportback will roll into showrooms in Germany and other European countries at the start of 2017. The A5 Sportback starts from €37,800 (US$42,500). The price for the S5 is €62,500 (US$70,300).