The 2015 Chevrolet Impala is now available in a bi-fuel configuration that can run on Compressed Natural Gas (CNG) or conventional gasoline fuel. But it gets more interesting than that, as the Bi-fuel Impala can also run on sewage, beer, and food scraps.
Cleveland, OH-based Quasar Energy Group has developed a method to convert organic waste into a renewable energy source known as biogas, which is the raw mixture of gases given off by the breakdown of organic materials kept in an environment lacking in oxygen. Methane gas is the resulting product, which is then processed to remove all carbon dioxide and impurities to make Renewable Natural Gas (RNG). When compressed, RNG is a direct replacement for CNG.
Source
GM Authority