The stunt at the Bundesplatz was staged by the Swiss Council for Accident Prevention (BFU) and a group called the Knights of the Road (Ritter der Strasse) to demonstrate a real-life predicament faced by motorists.
The demonstration in the Swiss capital was designed to show how to survive when a car plunges off the road and into a body of water.
The only solution to exit the vehicle is to open a window or to smash it, the safety groups said.
“Close to a quarter of the 464 people that we have credited (since 1969) for their courageous acts have intervened in this way,” Peter Matthys, president of Knights of the Road, told 20 Minutes newspaper.
“But we realize that very often people do not know what to do (in this kind of situation),” Matthys said.
Knights of the Road annually honours people who have acted to avoid the worst outcomes from motor vehicle accidents.
The demonstration showed that smashing a side window is the best way to get out of a vehicle under water if it won't open.
The pressure of the water makes it impossible to open doors and the windshield is too difficult to break open, the safety groups said.
The BFU recommends that motorists keep a hammer for breaking glass in the vehicle.