I named a birch boat using an anvil "The Crawdad". I placed the boat in water, rode around a bit, then broke it with a stone axe. When I scrolled over it in my hotbar, it's name was "Birch Boat". I did the same thing with a black bed: I named it "Joe's Bed", placed it, broke it, and saw that its name had reset. I suspected the same would occur for a minecart, so I named one "The Paladin"; however, it did not reset, fortunately.