I suppose we would need a copyrights/licensing attorney to confirm on this subject but I dont believe placing owners vehicles on a calendar would constitute breaking licensing rights. IF, we used the official logo graphic of the company or any official quote, I then see the need for permission and licensing.

If a film company had to pay for every car shown in a freeway scene for a movie, it would be a ridiculous feat.

Permission that I was talking about concerning the poster stems from wanting the permission of the picture owner to use, print and duplicate the image.