I have painted the floors in my last 2 garages with the RustOleum epoxy paint with great results. It is very durable - I have spilled numerous chemicals on it without incident, it has never stuck to any tires and it is very tough to scratch. It is also easy to clean - when I lived in NY, they used ash mixed in with the road salt. This concoction would get deposited in my garage all winter, making quite a mess. In the spring, I would break out the pressure washer and clean the floor - it would end up looking like new. I got one of those floor squeegees to get the water out after washing. Oil, paint, etc. spills wipe right up with no staining. You know how you can sweep a bare concrete floor 50 times and still get some dust each time? With this stuff, you can sweep the floor once and it is clean.

The key to a tough finish is: 1 - make sure you prepare the concrete according to the instructions before applying the paint, rinsing it completely and 2 - make sure you let the paint cure sufficiently before driving on it.