anti theft
 

I have heard from one of my friend that Navi System can be use as a anti theft device!Is it true?

Yes, some navigation systems have features that can act as a basic anti-theft device. For example:

Security PIN: Some systems require a PIN code to be entered before the unit can be used.
Tracking: Certain navigation systems have GPS tracking, which can help locate your vehicle if it's stolen.
However, this depends on the type of system installed. Not all navigation systems come with these features. Check the manual or contact the manufacturer of your unit to confirm.