B5/B4 would be compacts if they're not a bookable class on their own, so yes it would be a downgrade.

Can you even get the Ecosport with 4WD? And is 4WD part of the Q class description? I have seen an Ecosport in the 5* section at SFO (and it was being taken) so I'm not sure what car class it would be in — other than "avoid like the plague."

That said, I'd be more worried about a "prestigious" Buick Encore as it does have AWD and might end up in the higher class. Similarly, while a Rogue is a compact SUV, even an Equinox is a midsize.