Allowing for the fact that the purchase of a high quality car alarm could be one of the more expensive investments you will make, it is obviously important to you. However, even the very best car alarms may not be able to stop a determined and highly skilled car thief. Amateurs and first time opportunity car thieves will almost certainly be scared away when the alarm is activated, but many professional car thieves will see it as a challenge and persist in their attempt to steal your car, even with one of the best car alarms fitted.