So I have been using the calculator and when selecting Mercedes it says that each MSD reduces the MF by 0.0001 however when I talk to the Mercedes dealer they say it actually reduces it by 0.00007.

Are they wrong or is the calculator wrong? I also see that autopay reduces it by 0.0001 on the calculator but I had a different dealer say that it was that which was 0.00007.

the current mf on a 17 is .00047 or .00037 with auto-pay so the lowest you can get to with msd is .00001.
each MSD takes off .00007.
so if you starting with a .00037 you can do 6 msd to get to .00005. 7 msd would get you to .00001