I wonder if Elon actually has the resources to make a functional dry submarine car with capabilities as portrayed in the movie? With some consulting from marine engineers, his people could probably fabricate such a prototype out of aluminum. He and his companies probably couldn't afford to take the resources away from R&D to actually do this, however.

Top Gear made their submarine car Lotus, but it was considerably compromised as both a car and a submarine. Can't really be debonair when a stream of water is squirting onto your tuxedo trousers. It only held water out of the cockpit by having air pumped in at a high rate.