Vehicles now a day are becoming very necessary part of our life this is leading to increase in congested traffic conditions around the world. With our research in this domain of vehicle detection with image processing we are focusing on detection of vehicles. This is then combined with car size detection. Our approach is to first work on the feature of four wheeler i.e., windshield of the car. Then to work with saliency generation of the region of interest which will be containing only windshield part for the vehicles in the frame. With conversion of this frame into HSV color model. From HSV the saturation value within certain limit is kept for the segmentation then on from that leading to the detection of the vehicles in the given frame. Vehicle size detection we have considered eagle eye view for taking out area and on the basis of that deciding threshold for the vehicles into different categories. Categories of vehicles include small, medium, large vehicles for four wheelers.