My old car (C7 A6) had a start/stop button very similar to my S4, i.e. press to switch on ignition/engine, press again to switch off engine/ignition. But in the A6 if you pressed the button again after switching off the ignition it had the same effect as opening the door - it locked the steering, turned off the MMI and turned on the courtesy lights. This was useful at night, e.g. where you want the lights to find your keys but didn't want to open the door if it's cold and wet. It's the same on a (non keyless) 8V A3 - when you pull the ignition key out the MMI goes off and the lights come on. As far as I can tell the start button in the S4 either switches the ignition on or off, there's no "key out" setting. If you stop the car and press the button again it just switches the ignition back on. I can't find any way to turn on the interior lights and shut off the MMI without opening the door, which is rather annoying. I feel I'm missing something obvious - am I?!