The camera does not automatically come on when you are slowing down. That would be quite annoying if that is the case every time you stop at a light for example. Your sensor is however active, and the camera only turns on when your sensor detects you are close to an object. The trouble is that there is no visual cue that your sensor is on. And the tolerance to activate on the Solterra seems to be much higher (ie. you need to be much closer to an obstacle compared to other German cars that I have encountered). As stated above, when in doubt, press the camera button. I like the older Mercedes as there is a status bar both on the middle of dash and behind to let you know when the sensor is active.