I'm getting whatever my sig says at the bottom, but I do drive her carefully, never revved over 2900-3000 rpm, turbo should kick in around 1750 revs, you can feel it (just) its maxed out around 2800revs. Sounds like yours needs a good clean out maybe the injector pump tweaking a little and the turbo and pipes checking over, specially the small pipe that goes from turbo to injector pump.
Change the air filter twice a year at least, engine oil twice a year, keep the tyres firm, I have Grabber ATs on mine and she's happy at 38psi all round.
If I tow a 1200kg trailer, mpg drops to about 28 I'm happy if it stays above 30 usually.