A system and method of controlling the operation of a transmission using fuel consumption data. The system and method includes controlling the operation of a vehicle transmission which is operatively connected to an engine having operating characteristics and operatively connected to a transmission control module having access to a memory. Fuel consumption data for an engine is converted to engine efficiency loss data representative of the engine operating. A set of equations is determined to provide a pattern representative of the operating characteristics the engine. A transmission controller using the pattern determines a prospective operating condition of the transmission to provide fuel efficient operation of the engine.