Some models use sensors mounted in front of the front wheels, monitoring the lane markings. Other models use a camera mounted in top center of the windscreen for the same purpose. Both systems alert the driver by vibrations in the driver's seat, on the left or right half of the seat cushion, respectively.[9] Introduced with the 2005 model C4, later followed by 2008 C5 and 2013 C4 Picasso.