This paper investigates the impact of Cooperative Adaptive Cruise Control (CACC) on traffic-flow characteristics using the traffic-flow simulation model MIXIC. CACC is an extension of Adaptive Cruise Control (ACC), which allows vehicles to communicate with each other, enabling closer following distances and improved traffic stability. The study focuses on a highway-merging scenario from four to three lanes and finds that CACC improves traffic-flow stability and slightly increases traffic-flow efficiency compared to scenarios without equipped vehicles. CACC has the potential to increase highway capacity by minimizing time gaps between vehicles and improving string stability. However, the level of improvement depends on the penetration rate of CACC-equipped vehicles. The study also highlights that CACC can significantly enhance traffic-flow performance, especially in high-traffic conditions, by reducing time gaps and improving string stability. However, the presence of a dedicated CACC lane can lead to performance degradation if the penetration rate is low. The simulation results show that the number of shockwaves decreases with increasing CACC penetration, indicating improved traffic stability. The average speed on the links also increases, suggesting improved traffic throughput. However, the presence of a CACC lane can lead to performance degradation if the penetration rate is low. The study also notes that CACC can have a negative impact on traffic safety during merging processes, as close CACC platoons may prevent other vehicles from merging due to smaller gaps between vehicles. The paper concludes that CACC has the potential to improve traffic-flow characteristics, particularly in high-traffic conditions. However, further research is needed to address open issues such as the modeling of congestion and the interaction between traffic-flow effects and communication and sensor-system characteristics. The study also recommends solutions to mitigate the negative effects of CACC on merging processes, such as limiting the length of CACC platoons and implementing cooperative-merging applications.This paper investigates the impact of Cooperative Adaptive Cruise Control (CACC) on traffic-flow characteristics using the traffic-flow simulation model MIXIC. CACC is an extension of Adaptive Cruise Control (ACC), which allows vehicles to communicate with each other, enabling closer following distances and improved traffic stability. The study focuses on a highway-merging scenario from four to three lanes and finds that CACC improves traffic-flow stability and slightly increases traffic-flow efficiency compared to scenarios without equipped vehicles. CACC has the potential to increase highway capacity by minimizing time gaps between vehicles and improving string stability. However, the level of improvement depends on the penetration rate of CACC-equipped vehicles. The study also highlights that CACC can significantly enhance traffic-flow performance, especially in high-traffic conditions, by reducing time gaps and improving string stability. However, the presence of a dedicated CACC lane can lead to performance degradation if the penetration rate is low. The simulation results show that the number of shockwaves decreases with increasing CACC penetration, indicating improved traffic stability. The average speed on the links also increases, suggesting improved traffic throughput. However, the presence of a CACC lane can lead to performance degradation if the penetration rate is low. The study also notes that CACC can have a negative impact on traffic safety during merging processes, as close CACC platoons may prevent other vehicles from merging due to smaller gaps between vehicles. The paper concludes that CACC has the potential to improve traffic-flow characteristics, particularly in high-traffic conditions. However, further research is needed to address open issues such as the modeling of congestion and the interaction between traffic-flow effects and communication and sensor-system characteristics. The study also recommends solutions to mitigate the negative effects of CACC on merging processes, such as limiting the length of CACC platoons and implementing cooperative-merging applications.