Cool things with wheels since 2006
I don't think we need to go over all of the many reasons as to why this would never work, but there are so many that I'm surprised that anyone would even take this idea to the drawing stage.
Stevens was at the forefront of aesthetic design, but unlike his other work, this was just the manifestation of an idea. It was totally non-functioning as an integrated car/trailer/boat. It's not even clear what problem he was trying to solve. That said, it looks like they went forward with producing a prototype: http://www.macsmotorcitygarage.com/2016/02/02/the-brooks-stevens-evinrude-lakester/