I'm a platinum card holder that booked a rental a long time in advance, booked the highest class I could (A6 3.0 Premium Limousine), also added to comments that I was fine with a lower class, as long as it was a sporty vehicle. When I got there, the Sixt employee gave me two options, both station wagens (bmw 530 and A6), with nothing sporty about it. It felt like a joke really, when I explained him the car was a few classes lower than what I booked and paid for, he said I got a good deal and shouldn't complain about it.
When you go on the Sixt app right now, you can see that the class 'A6 avant' is a lot cheaper that 'A6 premium limousine' so yeah, I feel I didn't get what I deserve, especially when you are a platinum member, which gets a class upgrade by default.
EDIT:
Honestly, if was also Nordhorn that gave me a super sick car (BMW X6 m50d) and I totally forgot it was the branch in Nordhorn, so I'll switch my 1 star rating to a 5 star rating, as the kind gentleman called me up and was really excited about being able to give a car fanatic like myself, such a beautiful beast for the weekend.