My first guess is that while magnetized paint would indeed be possible, the charge would not be enough to do much in terms of repelling cars. But perhaps your idea could lead to two avenues. Magnetized paint would make it easy to have logos or signs attached to cars. And perhaps the frame of the car could be magnetized, esp. when engaging in an emergency stop, in a way that would reduce accidents.

I know that a thin layer of paint wouldn't create enough of a magnetic field to repel a car. However it could be used to give the car's body panels a charge so that it could help it repel dirt and pollen perhaps... sort of the opposite of that electric air filter you see on TV. But I think your best bet for repelling another car would be to create a high powered magnetic bumper that could work with a sonar like detection system and a capacitor power storage, so that when a low speed accident is about to occur the device will detect the upcomming impact, fire off the capacitor that is constantly charged by your altinator, which would super charge the magnet of both the cars involved with equal polarity at the exact moment of impact and ultimately repel each other. However, all cars would need to be fitted with this device for it to work. Plus all cars today are made from fiberglass and composite materials that are not magnetic, therefore it would be a trade off of weight vs safty to have such a system.

Magnetic fields drop in strength very quickly with distance. So if you made a field strong enough to have any repulsive effect against other car's fields, it would be so strong your tooth fillings would electrocute you as you moved your head around in it. Not to mention eyeglasses flying off your head, steel bits picked up from the road, etc.

But we could all have fantastic bumbers right now, if we demanded them. Instead, everybody buys cars with $2000 plastic bumpers that need replacement after the slightest impact. Look at the bumpers on "push trucks" they use at races: A big piece of steel that sticks out a couple of feet, with giant hunks of tire rubber mounted on it. Never damaged, never needs replacement.

Years ago I read about a plastic/polymer that had been invented that was so shock absorbing that you could drop an egg from two stories onto it and it would absorb the energy so the egg would not break. Why haven't the car manufacturers used that material for bumpers? It seems to me that would save countless lives as well as a lot of money in repairs.

the material you heard about is sorbathane. the problem is that it is very soft - like play dough. and it creeps over time. it would just drip off the car.

You can already get magnetic wall paint. They use it for childrens' rooms and such, where the kids can put magnetic letters and other fun stuff on the walls. I don't think you could make it strong enough to repel a moving car though!

But that would not really "prevent" the crash itself, even if such a monopole magnetic paint were available. You would only increase the interaction distance, but both cars would still suffer the shock and its consequences.

Magnetism should not be confused with electrostatic charge. An electrostatic field on an object might either repel or attract dirt and dust. A magnetic field would only affect magnetic substances such as iron or nickel dust.

If you're thinking of paint to add magnetism, that is only practical for very weak fields.

if you're thinking of paint that allows magnets to be attached to the car, a large percent of cars have steel bodies. Otherwise there is already paint that includes particles of ferromagnetic metal, which allow magnets to be stuck on the paint.