Shift control apparatus for vehicle step-variable automatic transmission

A shift control apparatus for controlling shifting actions of a step-variable automatic transmission for a vehicle, which has a plurality of selectable groups of forward-drive positions having respective different sets of speed ratios, each one of said plurality of selectable groups of forward-drive positions including at least one high-speed position each having a speed ratio which is different from that of each high-speed position of any other of said plurality of selectable groups, the shift control apparatus comprising:

• a drive-force-increase determining portion operable to determine whether it is necessary to increase a drive force of the vehicle with said automatic transmission placed in one of said at least one high-speed position;
• and
• a drive-position-group selecting portion operable to select one of said plurality of selectable groups of forward-drive positions which includes said at least one high-speed position each having the speed ratio higher than that of each high-speed position of any other of said plurality of selectable groups, when said drive-force-increase determining portion has determined that it is necessary to increase the drive force of the vehicle with said automatic transmission placed in one of said at least one high-speed position.