Hydrogen vehicles have been criticised, however, for using very high inputs to produce the fuel cells or combustion hydrogen. Some countries, such as Iceland and Denmark, are using renewable energy sources to produce hydrogen.

Most researchers agree that it will be many decades before an efficient and economic way of producing hydrogen for vehicle transportation will become available, and that other hybrids are probably more efficient means of transportation than hydrogen vehicles. If you are interested in purchasing a hydrogen run vehicle, visit the following manufacturers:

• BMW - makes the Hydrogen 7 and H2R, both powered by a dual-fuel Internal Combustion Engine;
• Daimler AG makes the F-Cell, based on the Mercedes-Benz A-Class;
• The Ford Focus FCV;
• General Motors has many models, including Hy-wire and the HydroGen3;
• Honda is experimenting with many varieties of alternative fuels and fuel cells, and has developed the FCX.
• Mazda, Toyota, Hyundai and Volkswagen are also currently developing hydrogen run vehicles.

Most of these vehicles are still in research and development phases, though, so you may have to wait a while longer before driving a car which runs on water!