Now, where did I leave that car? If you’ve ever found yourself confounded by this annoying problem, you know what a drag it can be to start hunting around a vast parking lot, laden with bags (or a child!) trying to figure out where the heck that car was. The good news is that with a smartphone, it really doesn’t have to be that way. There are quite a few Android apps promising to save your parking spot for you, but when I tested out some of the leading ones, I arrived at a surprising conclusion.