Why are cars the best transport?

When mechanical transportation was first developed this completely changed the way the world works. Vehicles back in the early 1900's were a lot cheaper and required less 'attention' than horses etc. Also travelling long distances, the horses would have to be swapped over to allow those to rest while the others carried on. This shows that cars were a lot more efficient than the original horse and cart. Now days the car has been developed to such an extent that they completely over rule horses. Also, not so much now, but recently they were an extremely cheap source of transport and also got you from A to B very fast without having to change over or allow it to rest.