The problem with using a large or small aperture is that you can push the exposure into an area that could result in a loss of detail in the shadows or highlights.
It also affects your depth of field; a wide open standard sports lens of 70-200mm f2.8 will have a very small depth of field so the vehicle being photographed could have areas that are out of focus, being outside of the depth of field (dof).
Remember the exposure triangle, shutter speed, aperture and ISO. If you adjust one you need to adjust the others to get an acceptable exposure. This can easily be seen if you select shutter or aperture priority.