With this autostick, you can manually put it in any gear you want at start and leave it there.
Say you put it in 1st, when you floor it, it will shift to 2nd at about 5500 RPM, then to 3rd at 5500 RPM etc.
When you let off the gas, it will downshift to the next lowest gear depending on speed, the computer knows when to downshift and not speed the engine past 5500.

This Mercedes transmission is computer controlled with a relative short term memory...Mercedes calls it "driver adaptic" the point being is that you can use the "autostick" function to "train" the transmission to shift at certain points... lets say you want it not to go all the way to red line but to upshift at 5k...you do it manualy a few times and the computer retains the idea and will do it on it's own even if you leave it in D...as long as you continue to drive with a similar level of aggressiveness.

The reverse is also true the more you drive like a Grandmother the more the transmission will react this way...most people to not realize or take advantage of this "adaptic" function...and even think there is something wrong with their transmission when it changes shift points...it is usually because it is responding to an input you have given such as down shifting to pass...or again if you are putting around and suddenly "get on it" do not be surprised if it acts "surprised". If you need it to respond aggressively while puttering...use the autostick or the kick down...the same is true of downshifting as well.