Thanks! This is the best explanation I’ve seen. Just bought a 2013 Cabrio with a puck and there is no mention of it in the manual.My 2012 Smart Fortwo Passion has the sensor; aka, the puck. The wiper lever has one down for intermitten, one up for slow and two up for fast. When in intermitten, it automatically adjusts to how much rain there is coming down. It increases in speed when it the rain becomes heavier. The light bar also has 'auto'. When it is put in this position, the lights come on automatically when it gets dark suddenly; rain or going through a tunnel. I don't know if it is the same in your car. I like the 'puck' and its features.