[diesel]

Yes your MPG is definitely low. I second the notion of checking the brakes for dragging. Also, do you still have LRR tires?

 

[diesel]

My CTD lifetime average is a hair over 40 MPG. Mostly highway driving, but at least 15% stop and go, traffic and hard acceleration.

 

[diesel]

Ok... Shall I set cruise control? I think there is a (mostly) flatish stretch on the way to Winston-Salem. I should be able to do this Sunday.

I have found that I get the best MPG with the cruise on

 

[diesel]

I noticed my fuel consumption increasing before I got the P0133 code. Then, after the dealer replaced the sensor and reset the fuel trim (and possibly updated the ecu) the fuel consumption dropped back to where I'd seen it when I first got the car two months ago. For me that means 30+ mpg around town.
I wonder about the sooting up of the O2 sensor as a cause of increased fuel consumption. Is it possible that a dirty sensor might cause a decrease in mileage without actually triggering a DTC?

This is a good observation. I think you might be onto something there.

 

[diesel]

So after all of the above, I seem to be a bit happier at roughly 35 MPG per tank (using ACar app to record mileage / gallons for calculations) and that's with my 37 mile drive to work with the 2000 ft elevation change. Not bad. I'll be going from NC to CT after thanksgiving, we'll see what happens. I am looking forward to seeing what kind of mileage I get on that trip as I don't get to do a lot of highway driving. (My work ride is 45-55 MPH roads, so not terrible, but it's still no highway.)
I also just had the NOX sensor recall done, we'll have to see if that affects anything.

I would think that most of what you lose going up the 2000 ft change, you would gain back coming back down.