Really nice tool - is it using traffic conditions right now? To elaborate, I first entered 4 hrs from Munich, then added another half an hour to it and got a counterintuitive map (see oalley.net/map/b3y): I would have expected the 4:30 hrs map to just extend a little further than the 4 hrs map, but in reality, some parts that I could have reached in 4 hrs are not reachable in 4:30 hrs. Any idea what's going on?

It seems to have issues with paths into or crossing the alps.