For successful operation of cooperative adaptive cruise control, the participating vehicles follow certain operational criteria. For truck platooning, the participating trucks are required to maintain a minimum inter-vehicular distance for efficient vehicle-to-vehicle communication and better fuel efficiency. In order to ensure such operations, it is necessary to study the behavior of other agents in the roadway that may disrupt a platooning chain. A car cut-in is generally regarded as a disruption to the natural flow of traffic. In general, a cut-in takes place when a vehicle from the adjacent lane comes between the host vehicle and a lead vehicle, and in turn becomes the lead vehicle. In this work, we have searched 2.1 million miles of naturalistic truck driving data to identify candidate close cut-in scenarios. Then we analyzed approximately 18,500 cut-in cases to study the effects of car cut-ins under different platooning operating conditions, including following distance and headway. This study demonstrates the probability of cut-ins as a function of the following distance. The study found that the probability of cut-in increases when the host vehicle keeps a following distance greater than 23.5 meters. It also shows that as a result of a cut-in, the host vehicle often needs to brake and increase distance with the original lead vehicle by 15.5 meters. This scenario shows how the following vehicle reacts to a cut-in scenario. We further analyzed the safety implications of cut-in situations by computing the changes in time to collision. As the following behavior of the driver is one of the major factors governing cut-ins, we also analyzed the typical following behavior of the drivers in terms of following distance, following duration, following headway, and following speed. We assessed the safety of typical following distances through mathematical models. We believe that the study will significantly benefit researchers working with platoon control systems and coordinated platooning models to develop strategies towards the successful deployment of platooning and countermeasures for cut ins.