Accelerator opening setting apparatus, method thereof and motor vehicle equipped with the apparatus

When the vehicle speed is within a range equal to or greater than a threshold value in which the vehicle is often cruised, a cruising accelerator opening is set as an accelerator opening needed to cruise the vehicle at the vehicle speed, and a cruise-purposed convergence opening (Acnv) corresponding to the amount of depression of an accelerator pedal requested of a driver is set at the time of cruise (Step 108, Step 110). An offset opening is calculated as a deviation between the set cruising accelerator opening and the set cruise-purposed convergence opening (Step 120). Then, the accelerator opening for calculating a power needed to run the vehicle is set at the sum of the offset opening and an pedal opening corresponding to the amount of depression of the accelerator pedal (Step 132).