From http://www.hyatt.com/gp/en/earning/with_car_partners.jsp "Hyatt Gold Passport members can receive attractive discounts at more than 4,000 Sixt car rental locations in 100 countries worldwide. Hyatt Gold Passport Platinum members receive a special 10% discount, and Diamond members receive a 15% discount, for every eligible Sixt rental. Diamond members are also entitled to a free of charge upgrade on availability. The discount is upon local availability of the respective car rental branch and cannot be combined with other promotional offers." Does this work in practice, i.e., can I book a car online on sixt.com and then expect to get a 15% discount off the quoted price as a Diamond member for showing my Diamond card when I show up at the rental counter in Germany? Is there a discount code? (not that I see place on sixt.com to enter one...) Or do I really need to call the German phone number listed in the next paragraph? "Call +49 (0) 1805 25 25 25 to book your rental. To receive your discount, be sure to show your Hyatt Gold Passport membership card when you pick up your vehicle. For more information on Sixt car rentals, visit Sixt rent a car."