Through the use of microelectronics the diesel truck can be more accurately and easily controlled. With the increased flexibility in timing it is possible to achieve a better fuel consumption vs. exhaust emissions strategy. With increased timing accuracy the engine is kept closer to the design optimum throughout its life. Through reprogramming at the engine factory, many specifications can be handled with one type of system and inventory. Field testing of the American Bosch microprocessor controlled governors has proven a number of convenient operation and driveability features as well.