They are divided into two major categories, electronic and physical. Electronic alarms are deterrents that draw attention to the vehicle when activated. Some physical devices include steering wheel and column locks, fuel cut-off switches and window etchings. Auto supply stores and car dealerships offer these items for sale. Each one has its own unique features which meet the needs of individual vehicle owners.
Some automobile clubs offer window etching as a security service.
Check with your local automobile club to determine if this is available. The idea behind window etching is that it makes the vehicle less attractive to a thief because of the high visibility of the vehicle's identification number on all of the automobiles windows. The etching makes it easier for the police to check ownership. Avoid hiding your keys under the hood or on the frame. A determined thief will find them.