I have a very similar problem. What is frustrating is I have a floor drain in the middle of the garage but not all the water flows in that direction. Like yours, one corner is low and that's where some of the water flows. Unfortunately, my walls are built on top of the floor, so I can't just mudjack that area unless I try and cut along the wall and I think I will be opening up a brand new can of worms. I have talked to some of the guys that do Epoxy and they said it is self leveling. However, it really depends how low your low spots are. Epoxy will only fill in so much.
I know there are floor levelers out there but I don't have much faith in them taking the abuse of driving on, etc. The only other alternative may be actually cutting out the bad section and re-pouring it.