[villagetinker]

I had very bad experience with muriatic acid. After using part of the acid in the container, I closed the FACTORY container, and stored it in the garage. Big mistake!! This was up North, and the temperature changes forced the acid vapor out of the container and did considerable damage to tools, wood shelving, drywall etc.
If you decide to do this yourself, but as little acid as possible, and make sure you know how to properly dispose of whatever is left over.

Personally I would try a good garage (concrete) cleaner, and a high pressure sprayer. Then once the floor was cleaned, I would coat it with the material I used in my garage. This was a CLEAR coating (I purchased at Sherwin Williams), that I added shark skin to. It gives a wet look to the concrete, and the shark skin provides a not skid finish.
Hope this helps.