There are several methods of producing a new transponder (chip) car key.  It is far easier and cheaper to copy an existing car key but if you’ve lost all the keys it is often possible to program a new key diagnostically. If that can’t be done it may be necessary to remove the immobiliser (aka ECU, EWS) and write information directly to the chip on the board.  This may require stripping off your dashboard or clocks to get to it.

In this picture we are EEPROM programming a new key into a Fiat Punto immobiliser.

car key programming
EEPROM programming a Fiat ECU