Maybe not a car but an amphibious vehicle would be cool. Cars on beaches have historically not been very durable/still there when you return although filling accident claim forms can be amusing. Near us a road floods each tide and visitors are always having cars washed out to sea. As soon as the water level rises too much they start to float and then are pulled out into deep water by the tide whilst their owners eat ice cream...thanks for the christmas card, novel as ever!