A vision system for a motor vehicle, comprising a pair of imaging devices (12a, 12b) forming a stereo imaging apparatus, a housing part to which said imaging devices (12a, 12b) are mounted, and a data processing apparatus adapted to perform rectification of images captured by said stereo imaging apparatus, stereo matching of rectified images, and detection of an object in the surrounding of the motor vehicle from stereo matched images, wherein said data processing device is adapted to perform, for image elements of a rectified image from one imaging device, a search for a best-matching image element in the corresponding rectified image from the other imaging device, said search covering a two-dimensional search area, said search yielding said vertical shift information from which a vertical shift from the image element to the best-matching image element is derivable, to calculate from said vertical shift information a vertical mismatch of one or more, or between, the imaging devices (12a, 12b), wherein said vertical mismatch comes from one or more of - a vertical windshield distortion between the imaging devices (12a, 12b); - a tilt of the optical axis of one or more of said imaging devices (12a, 12b) with respect to the image sensor plane; - a focal length difference or drift between the imaging devices (12a, 12b), and to calculate a vertical shift map comprising a plurality of image regions arranged in matrix form, where to each image region a vertical shift value of the image region under consideration is assigned, characterized in that said data processing device is adapted to extract contributions from a pitch angle error and/or a roll angle error from said vertical shift map by calculation, to calculate a residual shift map from said vertical shift map by subtracting contributions of a pitch angle error and/or a roll angle error from said vertical shift map, and to calculate said vertical mismatch from said residual shift map. wherein said data processing device is adapted to perform, for image elements of a rectified image from one imaging device, a search for a best-matching image element in the corresponding rectified image from the other imaging device, said search covering a two-dimensional search area, said search yielding said vertical shift information from which a vertical shift from the image element to the best-matching image element is derivable, to calculate from said vertical shift information a vertical mismatch of one or more, or between, the imaging devices (12a, 12b), wherein said vertical mismatch comes from one or more of - a vertical windshield distortion between the imaging devices (12a, 12b); - a tilt of the optical axis of one or more of said imaging devices (12a, 12b) with respect to the image sensor plane; - a focal length difference or drift between the imaging devices (12a, 12b), and to calculate a vertical shift map comprising a plurality of image regions arranged in matrix form, where to each image region a vertical shift value of the image region under consideration is assigned, characterized in that said data processing device is adapted to extract contributions from a pitch angle error and/or a roll angle error from said vertical shift map by calculation, to calculate a residual shift map from said vertical shift map by subtracting contributions of a pitch angle error and/or a roll angle error from said vertical shift map, and to calculate said vertical mismatch from said residual shift map. - a vertical windshield distortion between the imaging devices (12a, 12b); - a tilt of the optical axis of one or more of said imaging devices (12a, 12b) with respect to the image sensor plane; - a focal length difference or drift between the imaging devices (12a, 12b), and to calculate a vertical shift map comprising a plurality of image regions arranged in matrix form, where to each image region a vertical shift value of the image region under consideration is assigned, characterized in that said data processing device is adapted to extract contributions from a pitch angle error and/or a roll angle error from said vertical shift map by calculation, to calculate a residual shift map from said vertical shift map by subtracting contributions of a pitch angle error and/or a roll angle error from said vertical shift map, and to calculate said vertical mismatch from said residual shift map.