I don’t recall ever having lost track of where I parked my car, but I know people who occasionally do, particularly when they visit unfamiliar locations. Christoph had a cool idea on how to use OwnTracks to pinpoint the location where you last exited your vehicle.
OwnTracks for iOS (and very soon also OwnTracks for Android) has support for iBeacons which let it quite precisely locate an iBeacon and, in particular, fire a transition event when approaching or leaving a beacon.
The iBeacon itself I just chuck into the glove box of the car. When I get into the car or exit it, OwnTracks fires a transition event, and the app places the beacon icon on the map to indicate its current position.
The transition event itself is published to your MQTT broker and our Recorder, say, will store it accordingly. (It is a leave event as I am leaving the car; upon returning to the iBeacon in the car an appropriate enter event is fired.)
This way I always have the position of my car with me in case I once do forget where I’ve parked it.