Abstract: An electronic controller 16 for use in controlling vehicle operation comprises first and second memories 22,24, the first containing a plurality of control procedures and data values for controlling the operation of the controller for use with a plurality of different vehicle types, the second containing a plurality of pointers for selecting an appropriate control procedure and appropriate data values for the particular type to which the controller 16 is fitted. Therefore, a single controller 16 can be used with a plurality of different vehicle types. A portable programmer 20 communicates with a host computer 12 of a vehicle assembly line 1 and programs the controllers 16 under control of the host 12. A programming unit 50 is provided at service garages for reprogramming fitted controllers 16 or for programming replacement controllers 16', and can communicate with the host computer 12 for control thereby.