I have a 2009 Clubman S with convenience package. Sometimes I want to sit in the car or run the stereo with the windows open while I am working on the car for let's say 30 minutes. Both with the key in the dash and with the key just sitting in the center console, and with the car in "Accessory" mode (one push on the Start button with foot off brake pedal), the stereo shuts off after about 15 minutes.

Is there a way to keep the stereo on longer without turning the ignition on (two pushes of the Start button with foot off brake pedal), as it's always been my understanding that it is harmful to leave the ignition on for an extended time without starting the engine.