Jon, nice avatar - R22?
Peter (ALderMog), I haven't seriously looked into it, but I believe the traffic data is updated via a digital stream added to vhf FM broadcast radio, at least that's the impression I get when updating the SatNav. I'll spend some time one day and look it all up...
Peter (recycled teenager), nice idea, but I'd need at least two NT stickers every year. At present, the sticker is placed on a square of perspex, placed on the dash of whichever car we have used for our visit... Haven't lost it from the Mog yet, but one day...