The original post on how to find your radio code was referring to the Blaupunkt radio in a QP.
Many new car stereos have a "radio code". The code is an anti-theft measure that is designed to prevent someone from stealing your radio by in theory making the radio useless to them without the radio code.
Unfortunately you can buy the radio code for any car stereo for a few bucks on the Internet which makes the anti-theft value equal questionable.
2011 Tesla S
2005 Maserati Quattroporte
2004 Panoz Esperante
2001 Lincoln LS Sport