Better than stickers because you can remove them or add them to another vehicle.
How to Install Car Magnets

Installing car magnets takes only a couple of minutes. Before using them, find the best spot where customers will see your advertisements. Car magnets are usually installed in two places: 

Side of the vehicle – Side placement makes it easy for customers to see your magnetic sign while your vehicle is parked on the street. 
Back of the vehicle – If your vehicle is on the move, back placement lets the drivers behind you to see your message.  
Now it’s time to put the magnets in place. Here’s how to do it: 

Before installing, place the magnet on a flat magnetic surface to flatten it.  
Wipe the vehicle surface and back of the magnet with a wet cloth and detergent. Let dry.  
Place one end of the magnet in the desired position. Line up the other edge of the magnet, making sure that it’s flat against the metal surface.  
Note: Make sure that the vehicle surface is flat and rust-free. Avoid installing on surfaces where there are bumps and curves because these will prevent the magnet from sticking securely to your vehicle.  

Extend the Life of Car Magnets

Magnetic car signs are durable, but with proper care, you can use these signs for as long as two (2) years.  

When cleaning your vehicle, remove the magnet to clean debris from the vehicle surface. This will help extend the magnetic hold of the magnet and prevent any damage to the car sign.  

If you will not be using the car magnets for a long period, store them flat and away from direct sunlight.