Same as digger, i've been getting around upper 20's with my 1.6 120 vti. I emailed citroen who came back with "fuel consumption depends on a variety of factors" also told me if i wasn't happy to take the car into a dealer.
My mpg has gone from 29.5 to 28.2, total crap i think you'd agree. My old 1.4 civic gave me 38 mpg and that wasn't being careful.
I'm nursing the car at the moment to get the best i can out of it but it seems to be stuck at 28.2.
Anyway, i'm gibbering. Took it in today and the guy on the service desk asks me if i think a drop from 29.5 to 28.2 is bad. I tell him i think both aren't great and neither are within what citroen are quoting. He then appears with a ds4 brochure to check the quoted figures. I'm getting slightly pissed at this point. Tell him again, that i'd emailed citroen and they advised i bring it in if not happy. He eventually agreed to having it booked in for a service after having a chat with his colleague then disappearing again. Bit miffed about they're lack of customer service skills but a least it's booked in now.