AFP
United States patent number 8,947,202 relates to "a primary portable device [that] can access a vehicle by transmitting an activation message including a vehicle access credential to the vehicle." In plain English, this means being able to use your iPhone to unlock your car instead of fumbling for your keys - and even using it to start the engine as you enter it. The connection would be made via Bluetooth, according to the patent.
Apple was previously granted a similar patent that would let users unlock their vehicle using their iPhone along with an "accessory control," Apple Insider reports. This new patent, however, does away with the need for the additional device.
Of course, Apple applies for thousands of patents, most of which never make their way into finished products. (This patent to transform the iPhone's home button into a pop-up joystick, for example, is unlikely to ever see the light of day.) Many are applied for pre-emptively, or to snare competitors in litigation.
USPTO/Apple
There are other, more basic, issues. What if your phone battery dies? If you're not carrying a spare key, users could be stranded with no transportation and no way to contact assistance. That kind of problem suggests that even if Apple does follow this patent up, any commercial application is still several years off.