Given the speculations that autonomous vehicles are sure to take over the transport sectors in the near future, this study micro-simulates the impacts of automating the freight vehicle VAN using the micro-simulation software AIMSUN at SAE Level 4 on an existing motorway network in the United Kingdom using real road network conditions and traffic information. This study analyses the impacts of automation of vans in different levels of automation penetrations (0%, 25%, 50%, 75%, 100%) with heterogeneous traffic conditions on traffic parameters such as speed, time and different environmental factors such as CO2, NOx, PM and VOC. For better understanding the impacts of automation, analysis along the motorway was carried out along different stretches of the motorway between two junctions. In this study, the impacts of automation of van in different road characteristics such as congested stretches, stretches with slope and flat stretches were also analyzed in detail. The study highlights that with an increase in van automation penetrations, traffic parameters such as speed and time are positively impacted while negative impacts on environmental conditions are observed along the motorway stretches.