THE CLK does not have a conventional key and ignition lock, rather using a remote control device. This selectively unlocks the doors, boot and windows and is then inserted into the starter switch and turned lightly to the right to start the engine. A microprocessor compares codes before the ignition is turned on and, when it is, asks the remote to undertake a mathematical problem. All this happens in the space of half a second. Only when the two results are compared will the car start.