I have a rear seat companion with me some of the time and use the Audi universal rear seat cover. It is pricey but good for my needs. It fits very good less using the straps holding up the sides because the Q2 has no grab handles in the back!
The sides are firm enough for holding up without the straps. The only thing is I have to lift her in? I have no idea why as she could jump the whole car!
I have received the cover. I just fitted it very happy with it.
The only comment I would go with 3 holes for seat belt not 2. The hole is a bit tight for one side. But I will only have rear passengers infrequently