"We *def* don't recommended this, but Model S floats well enough to turn it into a boat for short periods of time. Thrust via wheel rotation."
It appears that Tesla cars are so well-made, so air-tight, that they will actually float for a spell and won't stall out like traditional, non-electric vehicles. Looks like this was sparked not a planned marketing pitch from the company, but from an amateur video from a Tesla owner in Kazakhstan, according to TheGuardian:
In addition to leading the automobile industry with electric vehicles, Mr. Musk is also pioneering private space exploration with SpaceX, solar energy with SolarCity, and has been the driving force behind many other ambitious projects (PayPal, HyperLoop). So would it really be a surprise if he ventured into amphibious vehicles next?
Full article from TheGuardian.
Learn more about Elon Musk at biography.com.