In 2013, Audi introduced on the market the Audi A3 Sportback g-tron as an answer for ecological vehicles.
But it was more than that.

The quest to lower emissions, the car-manufacturers were forced to find new ways to offer less polluting vehicles either by introducing electrified or electric vehicles or, as Audi did, tried a different approach.

The CNG is a compressed natural gas that can be associated with the regular gas from the stove. But to be stored in a larger quantity, it had to be compressed into special tanks. It was a good idea as long as it didn’t lose the content. The CNG was used for fleet vehicles and public transport, due to its complete combustion. When it burns, the CNG emits vaporous water and carbon dioxide, but not any NOX or other dangerous particles for health.

The Audi A3 g-tron was a very good offer for compact fleet cars. Moreover, it had two tanks: one for regular gasoline and a special one for the compressed gas. The small and economical engine was tuned for better fuel-efficiency and could seamlessly switch from gas to gasoline and back.

The main drawback of a CNG engine is that in cold weather it cannot start the engine. So, the computer-controlled fuel system automatically started on gasoline, and, after the engine was heated up, it switches on CNG.