Other Car Rental Programs/Partners (ie. Alamo, Enterprise, Sixt) - Sixt Germany ADAC Rate

Do I have to be a member of ADAC to take advantage of their discounted rates? Is it good enough to be a member of a club which is a reciprocal of ADAC?

ADAC is one of the very very few Sixt actually checks when you take the car. cannot suggest to take the risk. I saw to many times that they asked for it.

So no good even belonging to a reciprocal club?