If your car has speed-compensated volume (SCV), it means that the audio system will automatically adjust the volume based on the speed of the vehicle. This feature is designed to make it easier to hear the audio system at higher speeds, when outside noise is more prevalent.
To use SCV, simply turn on the feature in your car's audio settings. Once it's turned on, the system will automatically adjust the volume as needed. You can still manually adjust the volume up or down as desired, and SCV will continue to work in the background.
Overall, SCV is a helpful feature if you want to be able to hear your audio system better while driving at high speeds. It's easy to use and can be turned on or off as needed.