Strategies to minimize the fuel consumption of passenger cars during car-following scenarios

The way in which a vehicle is driven significantly affects its fuel consumption. This paper analyses the fuel-optimal driving strategies of a traditional vehicle equipped with a continuously variable transmission in car-following scenarios. A minimal-fuel-consumption problem is formulated, which is numerically solved using the Gauss pseudospectral method. The identified optimal manoeuvres were found to demonstrate two types of behaviour depending on the vehicle speed: pulse-and-gliding (PnG) and constant speed (CS). Further analyses indicate that the difference in behaviours mainly depends on the engine fuelling characteristics (both static and transient) and the road load. As the preceding vehicle’s speed increases, the optimal manoeuvre changes from partial PnG to full PnG, and finally to CS. In the full-PnG strategy, the engine switches between the minimum brake specific fuel consumption point and the idling point while the range error oscillates between its upper and lower bounds. The period, duty cycle percentage, and fuel economy improvement of the PnG strategy are analysed and presented.