Audi’s two latest natural-gas alternatives in the midsize category—the new A4 Avant g-tron (earlier post) and the new A5 Sportback g-tron—are now available for order in Europe. Both models are powered by a bivalent 2.0 TFSI engine developing 170 hp. Like the A3 Sportback g-tron that is already on the market (earlier post), they can run on a choice of the climate-friendly fuel Audi e-gas, conventional CNG (compressed natural gas) or gasoline.
A 2.0 TFSI engine powers both the A4 Avant g-tron and the A5 Sportback g-tron. It develops 125 kW (170 hp) and achieves torque of 270 N·m (199.1 lb-ft). The newly developed engine is based on the new gasoline-powered 2.0 TFSI with innovative combustion principle based on the Miller cycle (earlier post).
Over the standard cycle the A4 Avant g-tron with S tronic uses 3.8 kilograms of gas per 100 kilometers, with CO2 emissions of 102 grams per kilometer (164.2 g/mi) (in gasoline mode: 5.5 liters per 100 kilometers (42.8 mpg US) and 126 grams of CO2 per kilometer (202.8 g/mi)).
The figures for the A5 Sportback g-tron with S tronic are almost as good: In the gas mode, it too manages on just 3.8 kilograms per 100 kilometers, and achieves CO2 emissions of 102 grams per kilometer (164.2 g/mi). In gasoline mode, these figures are 5.6 liters per 100 kilometers (42.0 mpg US) and 126 grams of CO2 per kilometer (202.8 g/mi).
The drive unit’s high efficiency means low costs of ownership: Fuel costs compared with an equivalent gasoline engine are much lower, at around €4 (US $4.70) per 100 kilometers (62.1 mi) (Germany, as of: August 2017). The lower CO2 emissions also mean owners pay less in motor vehicle tax.
In conjunction with the manual six-speed transmission, the A5 Sportback g-tron accelerates from a standstill to 100 km/h (62.1 mph) in 8.5 seconds (A4 Avant g-tron: 8.5 seconds). Its top speed is 226 km/h (140.4 mph) (A4 Avant g-tron: 223 km/h (138.6 mph)).
The bivalent g-tron models can cover up to 500 kilometers (310.7 mi) on natural gas in the NEDC cycle. 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 more than 450 kilometers (279.6 mi) available.
The high-strength, safe gas tanks made from carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) are located beneath the rearward structure. They store 19 kilograms (41.9 lb) of gas at a pressure of 200 bar. Both models have a full-size luggage compartment: There is 415 liters (14.7 cu ft) of luggage capacity in the A4 Avant g-tron, and 390 liters (13.8 cu ft) in the A5 Sportback g-tron.
e-gas. The g-tron models are especially eco-friendly when running on Audi e-gas. (Earlier post.) This synthetic fuel is produced using renewable energy from water and CO2 or from organic residual materials such as straw and plant clippings. During its production, Audi e-gas binds exactly the amount of CO2 emitted by the car. Audi offers this fuel for three years as a standard feature to customers ordering a g-tron model by 31 May 2018.
They can fill up their g-tron model at any CNG filling station and pay the regular price. By feeding the computed volume of Audi e-gas into the natural gas grid, Audi ensures the green benefits of the program, including the corresponding reduction in CO2 emissions. With this deal, Audi is reducing the CO2 emissions of the g-tron fleet when running on gas by up to 80%.
Customers no longer require a special fuel card. Instead, Audi computes the volume automatically based on surveys and service data from the cars. TÜV Süd, a German testing and certification authority, monitors and certifies the process. Audi g-tron customers receive a document that confirms their car will be supplied with Audi e-gas and informs them about the certification.