Interesting, you clearly have a very unique driving style, perhaps you could share your secrets with us..?
I too have a 2WD Manual version, which I bought new in May 2014.
Since that time I have done 33,269 miles to date and used 859.3 gallons of Diesel, which by my maths equates to 39.13 mpg.
The trip computer will typically read around 43 mpg, but, as others have observed, it always over-reads by about 10%, which brings my actual mpg down to pretty much what I have calculated, i.e. just under 40 mpg.
Be very wary about relying on your onboard gizmos when it comes to fuel consumption..!