A naturalistic driving study can be defined as “A study undertaken to provide insight into driver behavior during everyday trips by recording details of the driver, the vehicle and the surroundings through unobtrusive data gathering equipment and without experimental control” (Van Schagen et al., 2011). The principle of naturalistic driving studies is close to the common sense reasoning that, in order to understand driving behavior it is important to monitor and observe drivers in their everyday driving activities, under a variety of conditions and for a long period of time. Indeed, experience indicates that participants in naturalistic driving experiments quickly forget the presence of cameras and sensors, which are as inconspicuous as possible, and behave as close to “natural” as possible: thus a “naturalistic driving study”.