It is not possible to load the ferries with cars and passengers in SS08 and I doubt that it will be possible in the next version. They are still working on the ship's dynamics and until they get this right, do not expect that they will bring on ship's stability as well.
Opening of doors and ramps would be a nice feature in relation to the mooring operation, but this is not possible in the 2008 version either.
However, it is a great game that you need to have if you just have the slightest interest for ships...
Regards
groennegaard