As with the OP my 2 door diesel auto has just clocked over 50,000km on a recent roadtrip. It was a trip characterised by high heat, high humidity and high loads thanks to all the gear the poor jeep was carrying. I fitted it with 33" tyres before the trip and had a dealership correct the speedo.
Fuel economy gradually declined from somewhere in the mid 11L/100km's to finally sit on 14L/100km over the trip. At first I thought it was a side effect of the bigger tyres with the air con constantly on and carrying excess weight in damn hot weather but after returning to cooler climates and unloading the car the economy did not improve in any way. I searched and found this thread and determined that there was definitely a fault of some kind with the car since comparable vehicles in posts on this thread were still in the 11-12L/100km range.
Additional searching lead me to some of the Liberty guys with the diesel motor cleaning the boost sensor (which is in a slightly different location on the Wrangler intake manifold). I removed mine to inspect it and confirmed that it was gummed absolutely solid with the sooty gunk that results from combining EGR with crankcase oil fumes. I gave it a clean with some carby cleaner and the fuel economy immediately dropped into the mid 12L/100km's. I have also cleaned the airflow sensor in the airbox to see if that offers additional improvement. Ultimately the intake manifold and EGR need to be removed and cleaned properly and the boost sensor probably needs replacing outright as it is still quite fouled with caked-on soot.
Anyone with a diesel who is experiencing fuel economy readings of 14 or 15L /100km should start first by giving this sensor a clean, it is almost certainly contributing to your issues. The Liberty guys recommend cleaning it at every service. After seeing how dirty mine was I'd probably agree.
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