A friend of mine just purchased a used Z-4 roadster. When asking me about adding a stereo system or plugging her iPod into the car's cigarette lighter, she told me that she had been warned by someone in the know that tapping into the wiring system for the purpose of powering after market accessories (like a car stereo, etc.) or plugging into the cigarette lighter (i.e. an iPod or cell phone charger) with anything other than a cigarette lighter could somehow cause damage to the electrical system of this BMW automobile.
1) Is there any truth to this, and if so, what is the explanation?
2) If not on this car, is it true for any BMW model or year and why?
3) If not for any, how do rumors like this get started (if you know)?
Thanks for your input.