http://youtube.com/watch?v=RKnL6NPyD40
This video is great, because you can also hear other police sirens as well, and the Rumbler is clearly much louder at a distance than any of the other sirens. I wasn't sure whether I should post this in the Audio Video forum, or this forum. I wish we'd get some of those Rumblers here in Louisville! You can't hear the current sirens in your car until they're almost right on top of you.