In order to prevent lane departures in car driving active safety devices have been developed. This paper assesses a new system designed to produce some motor priming (consisting of directional steering wheel vibrations) when a car is at risk of lane departure. The first objective was to determine if motor priming assistance can be of some benefit compared to more traditional auditory (lateralized sound) or vibratory (symmetric steering wheel oscillation) warning devices. Whilst on the one hand the motor priming mode was assumed to operate at the action level, on the other hand, other tested driving assistance devices were assumed to favour driving situation diagnosis. The second objective was to assess the possible advantage of using multimodal information by combining auditory warning with simple steering wheel vibration and motor priming. Observed behaviours showed that all tested devices improved drivers' steering performance; however, performance improvements were greater with a motor priming system. No performance enhancement was recorded when steering wheel vibration or motor priming systems were combined with auditory warning. This study confirms our hypothesis that the direct intervention of motor priming on motor action preparation is more effective than a simple warning which favours situation diagnosis. Multimodal information did not seem to improve drivers' performance in driving assistance systems for lateral control.