1. A system for controlling motive force of a vehicle having an engine and an automatic transmission connected to the engine to transmit engine torque to a drive shaft of the vehicle, comprising: operating condition detecting means for detecting operating conditions of the vehicle including at least an accelerator position and a vehicle speed, and operating conditions of the engine including at least an engine warmup state, an engine speed and an engine load; desired motive force determining means for determining a desired motive force to be generated by the vehicle based on at least the detected accelerator position and vehicle speed; option signal generating means for generating options signal in response to the detected engine operating condition; control mode selecting means for selecting one from among a plurality of predetermined control modes in response to the determined desired motive force and the options signal; desired engine output calculating means for calculating a desired output of the engine and a manipulated variable to be supplied to the automatic transmission in accordance with the selected control mode based on at least the calculated desired motive force; actuator control means for controlling operation of an actuator which regulates the output of the engine in response to the calculated desired output of the engine; and shift control means for controlling a gear ratio of the automatic transmission in response to the calculated manipulated variable.