Hallo Elke,
You can also ask on the DriveZim Facebook page, many travellers there and often people ask re ferries - you may get help there!
And don't knock the Toyota Landrover, last week I refilled the Cruiser at my usual fuel stop, and a new attendant that does not know the car, asked why the Landcruiser was taking in so much diesel - my regular attendant (that knows the car well) informed him that this was no ordinary Landcruiser, it was a TOYOTA Landcruiser, that's why it was taking in so much diesel. I'm still smiling!