[Burning_rubber]

I noticed that it only pulses when I'm stood behind the car - I.e. within range of the parking sensors. Over the course of 5 minutes it slows down, like it's going to sleep. If you walk away, it stops completely, and only the alarm LED under the rear-view mirror flashes.

Try it - lock your car (press lock once), then walk behind the car; he'll know you're checking him out

So, how about the cars without parking sensors like mine? I don't think is has anything to do with the sensors or the key being in range. The heartbeat just starts after locking the car and stays on for a couple of minutes regardless of your presence.