BMW has multiple anti-theft systems. The cars doors double lock; meaning that the only way to open the doors when this feature is used is with the key. You can lock someone inside the car and they will not be able to get out without breaking the windows. Coded Drive Away Protection is available on cars equiped with the On Board Computer. Once the four digit code is entered the car will not start even if you have the keys. You must enter the correct code for the car to start. All these features are available even without the optional factory alarm system that has a starter and ignition kill function. You basically have to use a tow truck to take the car once all these features are being used!