Dash lights.

The speedometer graphic when green indicates that cruise control is turned on.

1- The vehicle icon in the center below the vehicle's speed indicates that the Volt's radar is tracking a moving vehicle.

4 - The three dots correspond to distance maintained from the vehicle ahead when using ACC: Near (1 dot) - Middle Distance (2 dots) - Far (3 dots)

3. There are separate buttons on the steering wheel to power on the cruise control and to activate the cruise control. Once you have powered on the cruise control the Volt will retain this setting the next time you start the vehicle. When the icon is white the cruise control (or ACC) is powered on. When the icon is green the cruise control is active. New on the 2019 Volt with ACC; you can choose to use standard cruise control or ACC.