1998 Jaguar xj8 without a key that works you were told only Jaguar could provide a replacement key Does anyone know another key replacement option?

The ignition key has a transponder in it. Without the dealer programming the transponder, the key will not start the car. You can get a key made at your local Jaguar dealership for about $85 including the necessary programming. Some automotive locksmiths provide this service. I am an automotive locksmith and I cut and program the keys that you speak of.