We cannot; GTPlanet has no role in the development and production of Gran Turismo.
However we do have a Suggestions forum into which you can place your suggestions for cars (and tracks, and features) to be added to the game - originally created as a semi-direct line to the developers and with some evidence that it is at least referred to by them. As all of the cars you have noted in your post are already in that forum, you should visit the respective threads and "Like" the first post in order to vote upon them.