This article series has gone on longer than I expected, but in retrospect, it might be useful to cover car security for its own sake. I don't intend to scare anyone away from a car, as car security should be a lower priority than issues of safety, reliability, economy, and ease of use when making a decision. But once you have your car, it's good to know its strengths and weaknesses.
If you want to test your car's security, try this: Either inside your car or with the car window rolled down, lock the car up. Now, without your keys or remote, try to open the car. This test won't cover things like slim-jims and other tools that work inside the car door, but with a reach tool, and some other tools, pushing and pulling of knobs and buttons can be done inside the cabin.
The nature of the tools are such that there's a metal 'finger' that does all the work. While this can be covered in rubber, the grip is still quite weak. Pulling is easier than pushing. Curved surfaces are more difficult than sharp angles. Pinching, with a few exceptions, is not possible. Lateral motion is easier than vertical motion. So electronic locks where the unlock button is convex are better, because the finger slips off the middle of the button. GM's locks are mildly difficult, the ones that go up and down by the inside handle are tougher, as are the ones that you have to push forwards to unlock. Ones where the lock is underneath an arm rest are the toughest, in both getting to there, and seeing what you're doing.
There's two strategies for car security: Overt and covert. Both of them can be done very well, and can be done at the same time. Overt security, at its weakest, is the little sticker saying, 'Warning: Car alarm,' which really, isn't much; it's hard to see at times, and it's very likely that the only security is that sticker itself. Overt security, at its best, is something like the club. Not only is it very visible, it's something you can't fake. This is your first line of defense, because it's highly likely that the ne'er-do-well will skip over the car completely.
The alarm itself could be considered overt, but too many false alarms mean that the alarm is only there to hurt eardrums, not draw attention. Furthermore, I wouldn't consider alarms a good overt security because either they cause many false alarms, or the damage has already been done, and the car's already open. Locking the car back up quickly, while a good design, won't do anything for the scratched paint, torn rubber molding, or broken window.
Bad overt security, on the other hand, would be the type that makes its presence known, but is either ineffective in stopping a bit of knowledge, or is too overzealous in false positives. In the car world, this is the popup locks with slimjims and the car alarm that disables the trunk release. In the computer world, this is security through obscurity and unlockable archives because the password has been forgotten.
A good covert security is a last line of defense. It's a graceful failure. Something like Lojack only is effective once your car's already been stolen, but once it's been stolen, it's your only defense. Most car alarms disable the starter motor, which is okay. A few alarms have what I consider a good covert variant: they let the car start, but after a second, the car dies as if it had a bad fuel pump. This way, the thief incorrectly guesses the car's not drive-worthy, and won't be able to take off with it. Again, the car's already been broken into and hot-wired to get to this point, but once at this point, the security should stop failing.
And always, make sure you have a secondary key, and ideally, know how to disable the car alarm should it go haywire. Backups are a good thing, both for computers and for cars.
