Mine is a 204, 2017, long wheelbase, DSG and 4motion... Probably the heaviest of all models. Generally loaded with 2 adults, 2 kids, a medium dog a lot of heavy equipment, camping gear, bed frame, water tank,.... So a big heavy machine and probably as full as they get. I would don't consider myself a fast driver.
Most of the mileage I do is on French motorways, so that is 80 mph solid on the regulator, where I get 30 to 33 mpg (depending on wind, hills versus flat terrain,....) Urban will be 30 top, and it will drop into the mid 20's for short urban distances. UK motorways I can get 35mpg, sometimes a bit more.
40s could potentially be feasible in flat terrain, without traffic and staying well below the speed limit and at constant speed.
As for those getting 50mpg... NOT WITH MY VAN!! well, maybe downhill with a tailwind...