What is the circle in the middle of the Buick car key?

[Dora]

Buick car key's middle circle can remotely start the engine. The advantages of remote engine start are as follows: 1. High reliability: Remote engine start is structurally identical to manual ignition inside the vehicle, both utilizing an electric motor to start the engine, thus eliminating mechanical wear issues with heaters and significantly reducing failure rates. 2. Convenient usage: Although remote engine start cannot be timed like parking heaters, the remote start method is equally very convenient. The remote range is typically no less than 50 meters, allowing direct remote engine start from home or office if the vehicle is parked in a ground-level parking lot. 3. Automatic timing: Normally, a remotely started engine will automatically shut off after a period of inactivity, preventing potential fuel waste from forgotten shutdowns. 4. Whole vehicle heating: This function is similar to parking heaters, warming up the radiator coolant to effectively heat the cabin, engine, and windows alike.