I created this for Lego Ideas. The back wheels power the spinning cogs I put in for brushes, which can be adjusted in several directions. The front wheels can turn. The HOG steering is hidden in the warning light on top. To top it off, it is minifig scale.
This creation has crossed the 100 supporters milestone. If you like to see it as an official LEGO set, please support it here.
You can see a video exemplifying all the functions on youtube, here and I have more LEGO related videoes there.
Finally, for more pictures (including of an actual model) check the Bricksafe Gallery here