comfort and sport, mode switch..

[steveop]

2003 clk 320, drove lovely and smooth, right gear ant right speed and revs, smooth changes up and down,,,, used the sport and comfort button to try sport mode,, higher revs before changing gear, seems to change down earlier too, not as smooth either,,, put back to comfort mode, display in dash changes accordingly,, but appears to be stuck in sport mode,, is this possible,, what happens when this button is used,, is it just like an elecltronic remap or is their a physical mechanical valve or sensor used,,,, thankyou