I think Mazda is trying to fill in that niche, the recent 2019 Mazda3 is more refined and luxurious compared to competitors in it's class, but without the price tag of a German luxury.
The Mazda 3 is definitely not a "cheap car" in Europe. Mazda are positioning themselves slightly more upmarket in the premium sector, trying to nibble away at VW's dominance in this sector
The last time I tested a Mazda3 it fell squarely into the econobox category. What do you find luxurious about it? Or perhaps there's a secret trim level?