An improved car-following model considering velocity fluctuation of the immediately ahead car

• An improved car-following model considering velocity fluctuation of the immediately ahead car was proposed.
• The effects of velocity fluctuation of the immediately ahead car on traffic flow are investigated.
• It has significant effects on car-following behaviors and fuel consumptions.
• Considering it can improve traffic flow stability and reduce fuel consumptions.

To better describe car-following behaviors in the adaptive cruise control strategy and further increase roadway traffic mobility and reduce fuel consumptions, the linkage between velocity fluctuation of the immediately ahead car and the following car’s acceleration or deceleration is explored with respect to the measured car-following data by employing the gray correlation analysis theory and then an improved car-following model considering velocity fluctuation of the immediately ahead car on basis of the full velocity difference model is proposed. Numerical simulations are carried out and the effects of velocity fluctuation of the immediately ahead car on each car’s velocity, acceleration, vehicular gap, fuel consumptions and the total fuel consumptions of the whole car-following system with different time window lengths are investigated in detail. The results show that velocity fluctuation of the immediately ahead car has significant effects on car-following behaviors and fuel consumptions, and that considering velocity fluctuation of the immediately ahead car in designing the adaptive cruise control system can improve traffic flow stability and reduce fuel consumptions.