Benz dealer said I can’t put 10 msd on gle because it drops mf value low?
Is this true or what?
MF is already pretty low. Obviously, it cannot be below 0. If you do autopay, then the max you could do is 2-3 MSDs.
AWD: .00028 MF
RWD: .00036 MF
Can only be used to the max on a standard mf rate so they telling the truth
So how are we supposed to get best monthly payment
You would be getting the lowest possible mf at that point. So if you are set on getting a specific car, which would have a fixed residual and rebates, all that’s left is to negotiate the selling price.
I’m not sure you understand the purpose or function of MSDs. I suggest doing a little research. This board is full of valuable resources, you only need to search.
If you like, you can always ask the dealer to mark up the MF so that will allow you to apply the max (10) MSDs. 
At a macro level, MSDs work best on vehicles with moderate MF and high residual (so you can buy down MF) as opposed to exchanging a low MF for a RV reduction (which would benefit someone not using MSDs more).
I think you were being sarcastic, but that’s actually not a bad idea. Say the dealer marks it up for a profit of $1000, have them discount the car by $1000 in order to use the max MSDs. For the dealer it’s a wash, but for the buyer it’s extra savings.
I wonder if a dealer would do that? MSDs are already pretty complicated at some dealers, I don’t know how you would negotiate this. I guess this could be an ultra-leasehackr trick.