PRIORITY question at 115k do you have proof positive that the required (at 100k miles) timing belt change was done? If not your absolute #1 thing on the to do list is the TB job, very expensive to let that slide.
Comments on temp - obvious general one is welcome aboard and read Sir Sam's NOOB guide:
1. the typical failure mode for the OEM tstat is open or opening early which diverts too much coolant directly to the radiator where it cools, as it should, but prevents the coolant from reaching operating temp (176 F+). If your tstat has failed fully open the temp gauge will never reach the correct operating position of slightly left of dead vertical. If your tstat has failed opening early (as mine did) you can reach full operating temp (see gauge position) on hot days or under load (towing, grade, or AC running) and drop back when the load is removed. NOTE the KJ CRD tstat operates "backwards" IIRC such that what we call open on a normal tstat would be closed and on a normal tstat would result in engine overheating. If I was to bet your dealer had no clue how the CRD tstat operates and when the engine did not overheat they decided the tstat had not failed, like a normal one, closed and they were clearly without a doubt too lazy/stupid to bother to hook up the appropriate scanner to pull the actual temp and compare it to what it should be.
2. the only electrical problems that could relate would be a) a bad temp sending unit in the tstat head (easy test is an IR thermostat reading directly off the top of the tstat housing, b) a bad temp gauge (easy test run the FSM gauge check test); or 3) a bad signal to the temp gauge thru IIRC the Body Control Module or possibly the ECU (easy check same as in "a").
3. FYI there are some 05s that came from the factory with the temp gauge calibrated for a gas engine (see GDE discussion at
http://www.greendieselengineering.com/f ... st/19.page) but that causes the temp gauge to read high not low.
4. While I have participated in the inline tstat discussion and originally suggested the bypass hole addition to prevent temp spikes I elected not to run that mode and am running a replacement OEM tstat in an abundance of caution.
5. Your reported mpg is consistent or a bit high with a stock CRD that does not have a GDE tune which generally will up the mpg 10-20% plus do other good things for your engine. That said your speedometer, odometer, and EVIC mpg readings are poorly, at best, related. Any 1, 2 or all 3 may be off and off in different directions or som or all may be reasonably accurate; reality varies between vehicles. Best check is a run of 25-50 miles on a reasonably level and straight road using a GPS unit to check actual mileage and speed. Once you know actual GPS miles vs odometer miles you can figure an mpg correction factor for hand calculations and compare that with what your EVIC says.