The number of hybrid cars available is on the increase although they are still not as readily available as it is hoped they will be in the long term. And with technological advancements, electric cars are once again emerging as a viable alternative to the fuel guzzling and polluting vehicles that most of us drive today. Natural gas is a clean-burning alternative fossil fuel that can easily power internal combustion engine vehicles. The domestic abundance of natural gas makes it a highly attractive alternative fuel option. An leading alternative, biodiesel can be made from various sources including soybeans and biomass. Biodiesel can be used in most diesel powered cars without modification.