Comfort and Convenience
The on-board computer runs continuously once the ignition is on; the driver's input is not switching it on but cycling which readout the display shows, usually via a steering wheel or stalk control.
Safety and Driver Assistance
Electronic stability program works by comparing steering input with the car's actual yaw, then braking individual wheels. An attentive driver senses a slide only after it begins; ESP intervenes within that gap.
Multimedia and Connectivity
Bluetooth handles the wireless link itself — pairing the phone, then carrying call audio or streamed music to the system. Playback and dialling controls stay with the head unit or phone.