Sustainable fuels:  Any fuel produced from a renewable energy source.

Fossil fuels: Fuels such as oil which are produced from fossilised plant and animal remains.  Fossil fuels are non-renewable and are therefore a declining fuel source.  Some experts suggest that oil production will peak between 2025 and 2030, after which it will begin to decline.

Biomass: Any organic material with stored chemical energy.  Examples include corn, wheat, beets, wood, straw and vegetable oils.  Today, a wide variety of biomass-derived fuel products are under development.

Biofuel: Any liquid or gaseous fuel produced from biomass.

Biodiesel: A liquid fuel produced from biomass.

Synthetic diesel: A term sometimes used to indicate any non-fossil fuel.  Can be made from a variety of materials, eg: waste plastics.

Gas: Gas fuels include Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG) and Liquid Natural Gas (LNG), none of which are recommended by Scania.