Declining speeds and fuel consumption of cars Document from the Ministry of Equipment, Transport, Spatial Planning, Tourism and the Sea.
Relations between the speed and consumption of a vehicle (private car but applicable to other vehicles): curves and equations.
The lowest consumption per 100 km is not reached at the lowest speeds. For a current car, the optimum minimum consumption speed is between 70 and 90km / h.
The second half of 2002 marked a break in road safety statistics with an unprecedented drop in speeds and accidentology. This drop in speeds would also have contributed to the reduction in fuel consumption in the transportation sector.
For passenger cars (VP), this effect of the reduction in speeds is estimated at 0,9% at 2,2% according to the calculation methods, ie from 0,2 to 0,5 million tonnes of oil equivalent (Mtoe) less from an annual total consumption of 43 Mtep or between 9 and 22 liters of fuel saved per vehicle.
At the same time, traffic increased by 0,7% between 2002 and 2003. However, these figures should be considered with great caution because other factors influence the evolution of unit consumption upward (generalization of air conditioning or
lower speeds in the city) or downward (distribution of traffic by type of network for example).