Audi has released additional details concerning the A4 g-tron available exclusively in the more practical Avant body style. It will be available towards the end of next year with a special version of the newly developed four-cylinder, 2.0-liter TFSI engine rated at 170 PS (125 kW) and 270 Nm (199 lb-ft) of torque available from just 1,650 rpm. The engine’s pistons and valves have been specifically developed for gas operation and also to enable an optimal compression ratio. There’s also an electronic controller that lowers the high pressure of the gas that flows from the tank from 200 bar to just 5 to 10 bar in the engine.
This hardware setup enables the Audi A4 g-tron consume less than 4 kg of compressed natural gas per 100 km which according to the company’s calculations corresponds to just €4. CO2 emissions stand at less than 100 g/km and the car has a range of more than 500 km (310.7 miles) thanks to its 19-kg tank capacity. Once the tank’s level drops below 0.6 kg, the gasoline operation will be automatically activated and this will boost the range by an extra 450 km (279.6 miles).
Both the filler necks for the CNG and gasoline are located under a single tank flap and it’s important to mention that after refueling and whenever it’s cold outside, the car will start by using gasoline and then it will make the switch to compressed natural gas as fast as possible. There are four CNG tanks mounted in the back of the car and are held in place by tensioning straps which also protect them from damages.
In the Audi A4 g-tron, the spare wheel has been eliminated while the battery has been moved from the trunk to the engine compartment. Those CNG tanks have an operating pressure of 200 bar at 15 degrees Celsius and weigh 56% less than a traditional steel cylinder. That’s because these have an inner layer made from a gas-tight matrix of polyamide combined with a second layer manufactured from a composite winding of carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) while the third layer is made out of pure GFRP.