ASL in cars can refer to either Automatic Speed Limiter or Automatic Sound Leveling. Automatic Sound Leveling is a feature that adjusts the volume of the cars audio system based on the noise level inside the vehicle. It works by using a microphone in the car to sense the noise level and will increase or decrease the volume accordingly. On the other hand, Automatic Speed Limiter is a feature that can be used in situations where varying vehicle speed is likely but a maximum speed must not be exceeded. It is seen in brands like Jaguar and Volvo.