This report presents the results of an experiment to compare the consumption of primary energy by diesel, petrol and electric versions of a light van under urban traffic conditons. The experiment was carried out in Central London during 1978. In order to make fair comparison, the experiment was designed either to systematically control or measure factors such as driving style, road layout, traffic congestion and vehicle payload which were expected to influence energy consumption. Multiple regression analysis was used to establish vehicle differences and their sensitivities to the various independent variables. In particular, the characteristic variation of energy consumption with average speed for each vehicle was evaluated. The results showed 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 (17.58 km/h). The petrol vehicle was more efficient than the electric over most of the range of speeds observed in the experiment, but became less efficient at speeds 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.(A)

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