You may have noticed that when in Auto mode, the colourings of the Mode Indicator text changes between Grey and Green at somewhat random intervals.
Well, what it actually means is that it's switching between two different gear selection strategies. Essentially, there are 6 different modes, not 3 - for the automatic gear selection strategy, which is indicated here:
For each of the main modes (Normal / Sport / Track) you have an 'Eco' version. Which will up-shift aggressively early i.e. getting into 7th gear before you reach 30mph.
However, this mode only starts to come into effect some criteria are met
It starts after a period of more gentle driving, where:
The time it takes to enter this mode also varies depending on the main mode you have selected, thus:
In all cases, as soon as you do anything remotely aggressively, even stamping on the brake a bit hard, and it kicks out of GREEN Eco mode and goes back to 'whatever' mode you were in on the selector, which is then shown as ORANGE again.
The manual documents this here: