The emissions of climate gases from the transport sector and the measures that should be taken to reduce these emissions are debated both in Sweden and Internationally. Alternative fuels from renewable sources, new powertrains, etc. are discussed as possible options. Since there are only few studies available on this issue, it was of interest to carry out a project that would highlight some of these issues. In April 2001, the Swedish National Road Administration, SNRA, published a report over a well to wheel efficiency study, which had been carried out by the Swedish consultant company Ecotraffic. The report was published in Swedish. After the report was published, it became clear that there was an international interest for an English version of this report. While the work on the Swedish version of the report was in progress, and after the report was finished, several interesting international reports on the subject were published. Therefore, it was felt that a pure translation of the report without considering the most recent publications would have been somewhat negligent. It was also of interest to make some comparisons with the results from the most interesting studies.