The latest generation of anti-theft alarms feature warning horns that operate independently of the cars' own electrical systems, as well as time-controlled alarms that sound if a door is opened without authorization. Locking the car activates the alarm; unlocking the car turns it off. Some Audi models include tilt sensors in the anti-theft system, which detect any change in the car’s position (theft by transporting it) and sound the alarm. Initially the horn sounds for 30 seconds. In addition, the emergency flashers work continuously.