def get_car_road_position(left_fit, right_fit, xm_per_pix, UNWARPED_SIZE):

    """ Calculate position of the vehicle with respect to center of road
    Args:
        left_fit: `numpy.ndarray` second order linear regression of left lane line
        right_fit: `numpy.ndarray` second order linear regression of right lane line
        xm_per_pix: `float` [m/pix] vertical pixel to meters relation
        UNWARPED_SIZE: `tuple` Unwarped size (width, height)
    Returns:
        car_lane_pos: `float` [m] position of the vehicle with respect to center of road
    """

    if left_fit is None or right_fit is None: return None

    left_fitx  = left_fit[0]*UNWARPED_SIZE[1]**2 + left_fit[1]*UNWARPED_SIZE[1] + left_fit[2]
    right_fitx = right_fit[0]*UNWARPED_SIZE[1]**2 + right_fit[1]*UNWARPED_SIZE[1] + right_fit[2]
    x_distance_pix = int(left_fitx + abs(left_fitx - right_fitx)*0.5)

    car_lane_pos = x_distance_pix - UNWARPED_SIZE[0]*0.5
    car_lane_pos = car_lane_pos*xm_per_pix

    return car_lane_pos