Audi has come a long way from the A3 Sportback g-tron that they launched back in 2013. Since then, they’ve developed their own process for creating carbon-neutral fuel, in the form of e-gas. This new A4 Avant g-tron works in a way to harness that production process, but not in the way that you might expect.
Powering the A4 Avant g-tron is a 2.0 TFSI motor that has been tweaked to run on a CNG system. It still has a good 170 hp and 270 Nm of torque, making it a fairly spritely car, but the compression ratio and the valves have been changed to compensate for the downsides of CNG. The system hold 200 bar of pressure, but a regular drops it to between 5 and 10 bar for engine use.
There’s convenience as well, with a unified filler neck for both the CNG and regular fuel system. The regular fuel system is put in place to allow for cold starts, where the CNG system does not have a functional enough pressure to operate. Storage for the CNG system has also been improved upon by Audi, which uses a system that is 56% lighter than traditional steel tanks.
In order to refill with CNG, customers use an Audi specific e-gas card. This is where the carbon-neutral part comes in: while the cars may still operate on a compressed natural gas fuel, Audi replenishes this in the natural gas network with their carbon-neutral e-gas. So while a customer may not directly be using e-gas, they remain carbon neutral in a sense.
