High integrity localization system is an important challenge to improve safety for road vehicles. A way to meet the requirements is to fuse information from several sensors, from position and orientation sensors to motion, speed and acceleration sensors. This paper tackles the problem of vehicle motion estimation using monocular vision. A geometric model of the road is used to learn a texture patch in the current image, this patch is then tracked through the successive frames to estimate in real time the motion of the vehicle. The proposed method was assessed using a centimeter accuracy Real Time Kinematic GPS receiver.