It's not going to get 92 MPG Imperial (76 US MPG) in normal driving. These were professionals piloting the car to get that kind of economy.
A friend of mine consistently gets 4L/100 km (71 Imperial MPG, 59 US MPG) in a 9-year old Passat TDI wagon with close to 300k km (186k miles) on the odometer. But he also doesn't exceed 55 MPH on the highway...
I agree that those are not what one could expect for fuel economy during normal driving, but disagree that one needs to be a 'professional' to get those kinds of results. Last year I got 63 MPG (US) in my wife's TDI on a long trip at 55 MPH in California's Central Valley. The year before she got 72 MPG from near Seattle to outside SF (over 700 miles) on I-5 (up to 4310' elevation) by driving 55 on the flat and 50 uphill (I was following in my Dad's gas-hog old truck). Proper tuning, high tire pressure, a light foot and low speeds are all it takes...
BTW, our TDI is vented and I personally did the 'fill it to the rim' fueling on those trips. And since this car regularly gets 50 MPG fully loaded at 73-74 MPH indicated with A/C on this same Bay Area to Western Washington trip, I am confident the numbers are 'real'.
The potential fuel economy of a modern diesel is simply staggering!
My A3 TDI does 5L/100km with not so clean driving on the highway
(speedlimit is 75mph but I don't look at my speedo a lot)