They have incredibly accurate position data (GPS + radio beacons, etc) but that can't be used to control the engine map. The engine map has a finite number of

They have incredibly accurate position data (GPS + radio beacons, etc) but that can't be used to control the engine map. The engine map has a finite number of allowed inputs and a bunch of restrictions they must adhere to. For example it must be monotonic so that more throttle pedal input means more torque to the wheels. The engine map can not do anything based on track position, but the drivers regularly change engine maps while on track, especially in qualifying.