There are hints that one could be introduced in the future, but don't hold your breath. There would be a lot of work at both ends and a new boat to buy or build.
It is strongly advised that you do NOT bring your car over. There's only 9 miles of road on St Mary's, with none to speak of on the other islands.
The islands are perfectly suited to getting about by other means and retain their tranquility because of a lack of cars. For that reason there is no car ferry.
We aim to keep it that way.