The Redmi Note 14 Pro+ 5G can not be used as a car key. This feature allows you to use your smartphone to control your car, eliminating the need for a physical key. This technology works via Bluetooth or NFC, enabling a wireless connection between the phone and the vehicle. With supported vehicles, you can unlock the doors or start the engine by simply bringing the phone close to the car or placing it in a designated area inside the car. Some systems also allow you to share the key with others or control certain car functions remotely via your smartphone.