Hi,

I have a 96 525i, when I was driving down the road in the morning one of the colder ones here in New Zealand, I heard a beeping from the dash (3 beeps), on the display where it shows the temp it was flashing, then stopped.
The car is fine and there where no problems during the beeping.

Any ideas what that was?

Thanks
Sam.

After market radar detector? They beep.

I suspect you are hearing an alert that BMWs provide when the outside temp falls to 38 degrees F. This is to alert you to potential icing conditions - especially on bridges and overpasses. I know this was the case on my E30 but I'm not completely sure about my E39.

I agree with 'Filehorse', the feature's on all BMW's with OBC and later info systems though non- US models may vary.