[Tim in Scotland]

I have never used the steptronic/ sport mode in my OHEV but used it in all my Range Rovers to prevent up shifts when in low ratio gears off road, but the basic idea is that you move the shifter to the left to get a sequential gear change that can be manually activated by pushing the stick forwards to go up a gear and pull it backwards to drop a gear BUT that shift will only happen if the end result revs won’t be too low or too high. If you move the shift to the left then the shift pattern in auto is changed to a more sporty set of ratios were the ECU will allow the gearbox to hold onto revs for longer before upshifts, if you manually shift up or down the ECU checks you won’t be in a rev band to burst the engine or to drop the revs too low and will match the revs by a sort of pre-selection if the gears until it is safe/ not going to damage anything. So by moving the gear stick to the left you can have sporty automatic shifting of manual sequential pre-select shifts. It’s all too clever. In manual shift mode the ECU will also upshift for you if you get close to the Rev limiter so you cannot rev the nuts out of the geabox/engine.
It doesn’t apply in the Mini’s system but in the Range Rovers and other automatic Land Rovers it is a great additional control feature to prevent gear shifts when you might not want one offroad, it is very very effective in those situations compared to conventional automatics with a low ratio and no gear hold facility. In the V8 Supercharged Range Rovers the Sport mode can blip the throttle on downshifts AND spit a bit of flame and thunder out of the tailpipe as a party trick! It’s all in the program of the ECU!