I am thinking of having a car alarm installed that mimics that of a Benz. Some Benz has this sensor inside of them that reads a card that is the size of a credit card that a person puts into the wallet. I am trying to find if there is such aftermarket alarm.
My reason for this is because today a guy I know who has master keys for Nissan was able to start my car with his key, so it got me worried. And this key only works on my year model.

 

It would probably be cheaper to just buy the Benz. Aside from that, any alarm would do the trick. A key can only get him into the car, then the alarm would go off. Same case if someone broke a window...

 

Alarm turns off after 3 minutes. At that time he can get into the car put the car to on position and press that little button that most alarms have to shut it off if you loose the remote.

 

Well actually, No. The alarm *can* go off after 3 minutes, but if a zone is still violated, then it will continue to go off. Secondly, you tell everyone where that switch is? Do you leave a note on the dash pointing to it? Hope not, so therefore they wouldnt find it. Or if it would make you more secure use a ghost switch ie: door locks,fog lights,windows,etc...