 These were often wired to the car's ignition system, to explode when the car was started.Ignition triggering is now rare, as it is easy to detect and hard to install – interfering with the circuitry is time-consuming and car alarms can be triggered by drains on the car's electrical system.Also, the target can start the car remotely (inadvertently or otherwise), or the target may be a passenger who is a safe distance away when the ignition starts.