In summary, both incremental and revolutionary options are possible for reducing the GHG emissions impacts from motor vehicles. Incremental approaches are estimated to be capable of reducing emissions by up to about 25 percent over a several year period2. More dramatic and revolutionary options, such as powering electric vehicles from solar or wind power or converting that electricity to hydrogen to power fuel cell vehicles, could essentially eliminate GHG emissions from the full vehicle fuel cycle. However, there are major barriers to such a dramatic transition, including economic, technical, and consumer acceptance obstacles. To address the transportation energy and climate change challenge, both nearterm options–with more modest impacts but with a high chance of success–and longer-term but more dramatic options should be considered. Based on the resource base, land form, and demographic and socioeconomic conditions in a given setting, options for introducing new fuels and vehicle technologies can be selected that are the most effective and likely to be adopted.