We address the problem of shockwave formation in uncoordinated highway traffic. The problem is caused by the combination of heavy traffic and small traffic perturbations or unexpected drivers actions. We propose a novel distributed communication protocol that helps mitigate upstream shockwave formation even with extremely low system penetration rates. Based on traffic information ahead, the Cooperative Advanced Driver Assistance System (CADAS) recommends non-intuitive velocity reductions in order to redistribute traffic more uniformly and eliminate traffic peaks. Simulation results show that CADAS significantly increases the average velocity and therewith reduces the overall travel time and avoids unnecessary slowdowns. As a next step, for realism, we propose to apply CADAS to real traffic traces. Also, we extend the shockwave model from single to multiple lanes (to reduce accidents caused by lane switching).