The CAN Bus is the cars electronic network. (True techheads correct me if I stray, I only stay at Holiday Inns
) They, like your home computer, run a certain speed. The new radio requires the newer bus, which is faster at transferring data than ours. If you'll note, only new or newly reworked platforms, like the Caliber, Sebring, and Nitro get it this year. The LX wont get it til next year.