Hydrogen is considered to be an ideal energy carrier for low-carbon vehicles in the near future. It can be produced from water by using a variety of energy sources, such as solar, wind and nuclear, and it can be converted into useful energy efficiently and without detrimental environmental effects. The only by-product is water or water vapour in fuel cell vehicles, but small amounts of NOx are produced in combustion systems. Hydrogen can be used in any application in which fossil fuels are being used today, especially cars, buses and trucks. This paper considers how hydrogen can be combined with two other technologies; online vehicle monitoring and computer maps to give significant reduction in carbon emissions from combustion engines, especially on trucks.