Rented from Dusseldorf last weekend. Booked 'D' category which showed as 'Merc A class or similar'.
Used the preferred app to look at the list and chose my own car, ISTR there being 3-4 options. The only two I remember are Volvo V40 and Golf GTI.
Took the Golf, it turned out to be a GTI TCR version which I was incredibly pleased with. For those that don't know, the TCR is a special version of the GTI with a more powerful 286BHP engine and 5.6s 0-62mph. The one I had was fully loaded with all the options including performance pack (upgraded brakes etc), all ther driver assist options and the uprated Dynaudio sound system.
If you like hot-hatches then I'd recommend asking for one of these.