1. A vision system for a vehicle, said vision system comprising: a forward viewing camera configured to be disposed at a windshield of a vehicle equipped with said vision system; wherein, when disposed at the windshield of the equipped vehicle, said forward viewing camera has a field of view through the windshield of the equipped vehicle and is operable to capture image data; said forward viewing camera comprising an imaging array sensor and a lens; an image processor operable to process image data captured by said forward viewing camera; wherein, responsive at least in part to processing by said image processor of image data captured by said forward viewing camera, a road characteristic of a road along which the equipped vehicle is traveling is detected; wherein, responsive at least in part to processing by said image processor of image data captured by said forward viewing camera, other vehicles exterior the equipped vehicle are detected; wherein, responsive at least in part to processing by said image processor of image data captured by said forward viewing camera, road curvature of the road along which the equipped vehicle is traveling is determined; and wherein, responsive at least in part to processing by said image processor of image data captured by said forward viewing camera, a school bus stopping signal of a school bus present within the field of view of said forward viewing camera is detected.