The round black plastic tube affixed to the seat belt clasp above is the Escape Belt mechanism. It contains a cartridge with a salt pill; when enough water fills the car to dissolve the salt pill – more than a spilled beverage, mind you – a curved metal clip flips out of the top of the unit and depresses the button, unhooking the seatbelt. Voila, freedom.
We're not sure who is really the ideal demographic for this, but if you're interested, it's 29.95 euros ($39 US) and you can watch it at work in the video below. And if your ejection needs are even more intense, Fijen will be happy to sell you an Escape Hammer.