All cars do float. Most of them just not very long.

This is a good idea but from a cash stand point is quite prohibited. It would be expensive. You would need some sort of deployment system underneath the car, not unlike an air bag. I see two problems to over come. First, how does the vehicle know when it is in the water and not in the rain? Some type of pressure recognition system might work. Plus, another problem arises when you take into account the weight of the vehicle and the amount of floatation surface to keep the vehicle above water. I am not sure you could pack enough deployed floatation surface underneath the vehicle to compensate for the weight. Now maybe, with some help from nano technology, you could develop a surface strong and small enough to do the job. You might want to go to the Nano Tech Conference on Sept. 20 in Vegas and float your idea there.

The main problem when a car hits the water is getting out in a hurry. Perhaps some adaptation of the fighter plane system where the canopy is blasted off to permit a clean ejection of the pilot would work. If the driver could push an emergency button to blast off the top of the car, the passengers could get out quickly and swim to safety. Of course, disoriented drivers in other situations might create spectacular effects if some safety system is not incorporated.

good idea. what i would suggest is work on hovercrafting vehicles of the future that float on air, run on land and levitate on water. They can be used for fighting (if at all it happens) or as planes cum ships cum cars. Trillions of dollars will be saved every day as there would be no more planes people just need to take their hovercar and fly just like a car...

How to make it happen? Thats your problem

Aside from the problems of control in traffic which, in a hovercraft, is substantial, a hovercraft built to match the speeds of aircraft would probably murder more drivers in less time than an atomic explosion.

An ejection feature is good only around people who would not use it as a prank on the driver or owner of the car in question. (For example, you can imagine what older children may do once they find out about this built-in gizmo.) Therefore, a sensor that would automatically eject the driver (and passengers, if any) under the relevant circumstances must be developed and installed.

Perhaps a lightweight foam could be injected into the body panels to make the vehicle float. The foam might also increase the safety factors in accidents by absorbing more of the impact energy.

I like the futuristic movie with Sandra Bullock, Sylvester Stalone, and Wesley Snipes where a foam fills the interior of a car during impact to immobilize the occupants.

There are some water-based foams out there. Foam floats. Breathing might be encouraged by compartmentalizing the foam with deployable plastic sheets (head liner). So no matter how big or small the person is they would be covered first by the headliner, then by the side panels. The top foam block would be jettisoned along with the roof of the vehicle shortly after impact to insure passengers have air to breath.

The foam injected into the body panels would keep the vehicle afloat. While the side panels would liquify by dispersion of a chemical agent, allowing passengers to regain their mobility.

Fast acting foams are currently toxic, but the future holds much promise.

You people are making this much harder than necessary. All you need is a car that has a passenger compartment that doesn't leak. Cars sink because they leak and fill with water. This is often due mostly to the ventilation system, which could be redesigned to prevent flooding. The seals around the door could be a problem too, but probably not as bad as the holes through it, like the door handles. If cars were required to be flood resistant, they could do it, but of course it would add cost.

If the car was made lighter in general, (which would be good for performance too) the car might float high enough that you could open the windows and get out without flooding the car. Otherwise, a sun roof would make a good emergency escape hatch. There's no need for it to "eject", it just has to be possible to manually open it.

I like junkstopshere's idea. I already suggested foam as a safety feature in an earlier post. If the body were (recyclable) plastic instead of metal, there'd be no rust issues, and the foam would add strength, crash protection and flotation in an accident. VW used to have a TV ad in which a Beetle was floating--that car was tight. Check valves on ventilation openings could stop water infiltration.

If you make cars safer, do you make the drivers safer? Or do the drivers take more risks because they feel safer?

How many cars a year end up in water endangering the driver and passengers? Imagine all cars could float - then imagine how many will end up in water. Joyriders would drive cars into rivers just for the hell of it. Two tons of metal floating downstream towards a group of kids in canoes.