The “CarKey” string was found inside the beta of iOS 13.4 at the beginning of February, suggesting that Apple might be working on a feature that would allow users to unlock their cars using an iPhone.
According to recent reports, based on evidence found inside the iOS 14 code, Apple is allegedly working with BMW to become the first carmaker to support this upcoming iPhone feature.
Similarly to CarPlay, the feature is expected to be called CarKey. BMW was among the first manufacturers to adopt CarPlay, so it would make sense to also be among the first ones to offer CarKey features.
9to5mac reports that features could include not only locking or unlocking the vehicle, but also starting it up. These CarKeys would be stored inside the Wallet app on the iPhone, and could be shared with others via Messages.