I thought my mileage was low at 16,000
I've had it for just over 2 years. A couple things you may want to think about are a fomoto oil drain valve from greg at lubrication specialists and maybe a Amsoil air filter. They're cleanable and are supposed to allow more airflow. I can hear my turbo better 
If you have a shutter at 55 as you just let up on the peddle from a brisk start it's air in the fuel filter head. A lift pump is the answere but could void your warranty. The air causes other drivability issues too like a "seems forever lag" when starting from a stop. My fuel mileage in the city with short trips is twice what my Cherokees got at 20-22 summer 
and I'm pleased with that. But highway is only 24 at the most one time and that's not so good but I don't do much of that yet 