As I mentioned before, it slows down before the 45 mph speed limit sign. I'll have to measure but I think it's about 200 feet.yes, that's nice and all, but how /far/ past the 45mph speed sign did it slow down? for me, it's well inside the 45zone before it even starts to slow... it's a speeding ticket waiting to happen. I mean, really, I have to look up from my phone, move my coffee to the other hand and slow the cardown before it does it on its own. lol.