Which anti theft system is good for cars. Mechanical gear lock or electrical systems...or you have other ideas?

A combination of mechanical lock as well as electrical would do to prevent thefts. No single system is foolproof.

mechanical locks can sometimes be broken depending on what type. personally, i went with a stealth security system on my 07 mazda 3 and i love it. its easy to use and it has features like valet mode where you hit a button on the remote and the car will only stay running for five minutes after you take the key out.

it should be like if you touch the vehicle for more than a given amount of time, it should give you a little jolt of electricity...That'll scare them off...