Superconducting levitation and transportation

One of the properties of superconductors is that they don't allow a magnetic field to pass through them - this is what allows a small piece of supercoductor to float above a magnet.

Even when superconductors are used in maglev trains they are used for a different reason. In the tracks are permanent magnets, in the train is a magnetic coil repelling these magnets, supercoductor magnets could be used here because it is possible to make a very large electromagnet with no loss of power due to heating. But because of the difficulty of cooling the supercoductor it may be cheaper to use a regular magnet and waste the heat.

It's certainly possible to levitate a car using a magnet - junkyard cranes do it all the time!