Hi Rakuli! I liked this idea so much that I thought it worthy of a proper response. So I had to join your forums.
Magnetic levitation already exists, and can be used to create efficient transport, such as Maglev trains. The reduction in friction gives such vehicles the potential to reach very high speeds.
The problem with your idea is energy conservation. It's seductive to see the levitating paperclip, and think that this force can be harnessed for free energy. But one of the most fundamental laws of physics states that
energy is conserved. Energy can be neither created nor destroyed, only changed from one form into another. The total amount of energy in the universe is a constant (and most of it is tied up in the form of mass).
What you're describing is a perpetual motion machine: a device that creates endless motion, without requiring any energy input (or force, if you prefer). Early scientists (back when they were all philosophers) were fascinated by the idea of perpetual motion. But nowadays, we believe that perpetual motion is impossible, because it would violate the law of conservation of energy.
There are many practical problems with your idea, such as how you'd prevent the cars from flipping over. But let's open our minds for a moment: suppose you could overcome these problems, and suppose it was economically viable. What would happen?
Well, the strength of your magnets would weaken over time: potential energy of the magnets would be changed into kinetic energy of the vehicle. The more you used the roads, the weaker their magnetism would become.
You could use electromagnets, of course, but then you need a power supply (note the interesting relationship between magnetism, movement, and electricity: moving a magnet can create electricity, or electricity can move the magnet). This is what the Maglev trains do, but that electricity is not free.
So, although magnetic levitation can reduce friction, it's not a source of free energy. Magnets are neat, but they're not magical.
Check out the Wikipedia entry on perpetual motion techniques (involving magnets):
http://en.wikipedia.org/wiki/Perpetual_motion#TechniquesMagnetic levitation:
http://en.wikipedia.org/wiki/Magnetic_levitationMaglev trains:
http://en.wikipedia.org/wiki/Maglev_train#Maglev_vs._conventional_trains