Control of a vehicle having an automatic transmission to compensate for ambient air density

A controller configured to control an automatic transmission of a vehicle, the controller comprising:

• an input arranged to receive a signal indicative of a vehicle operating mode;
• a base map module configured to obtain a base map defining gear shift points for the transmission based on the indicated vehicle operating mode;
• a torque loss map module configured to obtain a torque loss map defining gear shift points for the transmission based on a predetermined minimum value of air density;
• a comparator configured to compare the base map with the torque loss map to determine whether the base map defines gear shift points at higher engine speeds than the corresponding gear shift points defined by the torque loss map;
• and
• an output configured to issue control commands for controlling the transmission based on the base map if the base map defines gear shift points at higher engine speeds than the corresponding gear shift points defined by the torque loss map,
• wherein the controller is configured to obtain a signal indicative of a gradient of a surface on which the vehicle is positioned by estimating a gradient of a surface on which the vehicle is positioned, or receiving a signal indicative of a gradient of a surface on which the vehicle is positioned.