Motivation – This paper is based on a research project which examines the way car drivers and automated devices cooperate to achieve lateral control of a vehicle. A theoretical classification of automotive devices in terms of human-machine cooperation is presented. Mutual control and function delegation modes are specifically investigated in three experimental studies. Research approach – All three experiments were conducted using a driving simulator. Driver behaviour was studied under normal driving conditions and in critical situations, with or without the intervention of assistance devices designed to improve lateral control. A new way to help drivers when lane departure was imminent, called motor priming was the main focus of the project up till now. Findings/Design – Initial results suggest that a motor priming device (asymmetric steering wheel vibrations) is more effective than more traditional warning devices. Preliminary findings also suggest that some negative behaviour...