I have an rMBP 15" late 2013 with the 512GB PCIe-based flash storage drive, and the reported amount of used drive space does not make sense. A screenshot is below. The storage summary states 414.81GB free of 499.05GB, so that calculates to 84.24GB used. Below that, it reports Apps are using 231.48GB (this is much more than 84.24GB). I have OS X Yosemite installed with only a few additional apps (Xcode, iLife, Firefox, and Google Chrome). How can apps be using over 200GB?