Originally Posted by dkl

The Business CD radio that have the additional BC button means that you have an "upgraded" On-Board Computer with 4 additional functions, which was part of the premium package. Those without the BC button still get the basic On-Board computer function displayed in the instrument cluster such as Outside Temp, Average MPG, Distance til empty, and Average MPH. The upgraded Computer basically get you Memo, Speed reached/exceeded alert, timer for Ventilation control, etc...