The traditional, metal car key has been rapidly falling by the wayside in recent years. Where the devices used to be vital for opening a vehicle's doors and getting the engine started, today the latest models have replaced that simplicity with an electronic gadget for owners to keep in their pocket. The next step could even make that obsolete and move control to a person's smartphone, at least if Apple does anything with a recently filed patent. The technology giant's solution would let owners control their vehicle from a smartphone over Bluetooth, Wifi or the cellular network. The patent mentions obvious uses like unlocking the doors and starting the engine. Apple also outlines sharing access with other devices to let more than one person use the car (pictured above). Since each phone is an identifier, the model could theoretically adjust the seats and mirrors to the right preferences as someone approaches. Of course, security would seem to be a problem. Apple says that access is limited by using a passcode, but there's no mention of what would happen if the smartphone's battery dies, it breaks or gets stolen. Presumably, owners would be back to the old days of getting in with a key.