I have SPG Gold - the hard way - but then also granted via AMEX Platinum - Match via Account Link to Marriott Gold - Match Marriott Gold to Best Western Diamond Select. When signing up for Sixt - you can do a status match - I matched to Gold at sign up. I sent an email to email@example.com
provided my Sixt Account Number, Best Western Diamond Select Number and a screen shot for the Best Western Account Info - showing my status and Account Number.
on April 7, 2018