Its not true. Your ignition key may have a chip in it needed to start, your car. Dont loose it. If you do . You can get a new one from a dealer. However they are not cheap.
it might be true...it depends on what year caddy you have. if its an 07 or newer with push button start, you will need the key fob to start the vehicle. if it doesn't have push button start, then you do not need the remote to start it