What does it prevent? At most it makes you fall in the water in the correct orientation.
At the price of your passenger seats being occupied by gas tanks, that surely are safe in a collision that's far more likely occurrence.
It's PR stunt, nothing more.
> At most it makes you fall in the water in the correct orientation.
They showed a still of the submarine car from James Bond as inspiration for this.
That's the roadster they should have built. This compressed air jumping thing is impractical and dangerous and will never be road legal. But a submersible car would have actual practical uses, increase survivability in several accident situations and not face the same regulatory hurdles.
If they were actually trying to build something cool I think that would be the play, but everything Elon does now is to bump stock price