Features like real-time location tracking and remote unlocks thankfully didn't work, but it was still serious -- you effectively had a window into the lives of other Mercedes owners. The firm hasn't commented on the report as of this writing.

Mercedes took the app offline for "site maintenance" a few hours after the problem began. Even so, this illustrates the risks that come with tying car data to personal accounts. An error like this, or a data breach, could easily broadcast sensitive info to the wrong people. That may become a sore point as car sharing and other connected car services become relatively commonplace.