In order to protect against theft, more and more vehicles are being equipped with systems that are primed and deactivated again by means of a coded radio remote control and sound an audible alarm when unauthorised entry is detected by contacts on the doors, engine compartment and luggage compartment or by ultrasonic motion sensors or current consumers in the vehicle's interior. The ultrasonic system also detects attempted vehicle entry through a broken window. The interior monitoring system can be turned off if, for example, animals have to be left inside the car for a short time. The latest generation of anti-theft alarms has a warning horn that operates independently of the car’s own electrical system and a time-controlled alarm that sounds in response to the unauthorised opening of a door. Locking the car primes the alarm, unlocking the car turns it off. Some Volkswagen models include tilt sensors as part of the anti-theft alarm system. If these detect any change in the car’s position (caused by an attempt to tow it away) the alarm will sound. Initially, the horn sounds intermittently for 30 seconds and the hazard warning lights flash continuously. The anti-theft alarm system with electronic immobiliser offers an optimum level of protection against vehicle theft. Audible and visual warning signals attract the attention of passers-by and frighten thieves away. An extra layer of security is provided by the tow-away protection's tilt sensor. The interior monitoring system protects against unauthorised or forcible access to the interior, engine compartment or luggage compartment.