The results showed that the diesel vehicle to be considerably more efficient in its use of primary energy than either the petrol or the electric vehicle, the ratio of energy consumption (diesel:petrol:electric) being 100:185:198 at the average speed observed during the experiment, but became less efficient at speed below about 14 km/h (ie in heavy traffic). The energy consumption figures produced are based on present-day production processes using natural oil as the source of both liquid fuels and electricity. While they still apply if electricity is assumed to be generated from coal instead of oil, they could be altered by the use of alternative energy source or production process assumptions