Fuel economy and energy consumption of hybrid and plug-in hybrid cars in Nordic climate conditions

VTT is conducting a field test with two Toyota Prius HEV's in Nordic driving conditions. The other car is factory stock, the other is fitted with additional battery capacity that can be charged form grid. An assessment of the potential for using electricity and lower the fuel use was made by selecting trip recordings of six drivers from the pool of drivers that use these cars. The analysis entailed also the influence of ambient temperature, as it was found to have a marked negative impact on fuel economy. For long-distance commuting the best reduction rate for fuel use was observed with the driver having one-way trip about the same (40 km) as the all-electric range offered by the add-on battery. Even larger reduction rates up to more than 50 % were observed in short-distance commuting. Overall, fuel savings were some 30 % for the long-distance commuters and about 40 % for the other group.