employed for the present invention the ecm 610 can be one or more microprocessors and other associated components such as memory devices which store data and program instructions the ecm 610 generally receives input signals from various sensors throughout the vehicle as well as possible external input data from end users the ecm 610 then reads the program instructions and executes the instructions to perform data monitoring logging and control functions in accordance with the input signals and external input data the ecm 610 sends control data to an output port which relays output signals to a variety of actuators controlling the engine or the scr system generally depicted by the engine controls 800 and the scr system controls 900 in general the present invention can be implemented with most commercially available ecm 39 s and no changes to the ecm will be required although this exemplary embodiment includes an ecm any system of controlling operation of engine components and after treatment devices according to specified instructions may be employed to implement the present invention according to the exemplary embodiment of the present invention the end user or some input mechanism transmits the unit price of diesel fuel 500 and the unit price of urea 510 as input parameters into the ecm 610 through the input device 600 the input device 600 may include but is not limited to a computer personal digital assistant pda or other entry device with a data link connected physically wirelessly or by any data transmission method to the ecm 610 moreover the input device 600 may include an automated system or network which transmits data to the.