Newer trucks can't handle extreme cold?

You would need Kerosene at that point. Essentially jet fuel.

Im not sure how a deisel will taste that stuff at -48... it should flow well enough because Airliners are at 45000 feet and colder than that most all the time.

 

Ive gotten to -50 per the dash in my cab and it's cold. You must have two or three layers of scarfing over your face, (This was before 9-11 and future use of face covers in Afghanistan etc) because the air coming into your nose gradually freezes you inside the passages towards the lungs. When you cannot feel your face in 15 minutes it's time to get inside.

Took me a hour to hot fuel that truck in central southdakota that night, it was a older pump and I had her flat out at idle. Cab and sleeper temp was around 68ish. Alternator was pulled down to about 11 volts. And the fuel waste must have been 30 or more gallons over that hour on top of the need to fill the tanks.

Fuel mileage became meaningless at that point to us and to FFE thank goodness. But I estimate it in the low 4's at that time. Usually high 6's

 

This is kind of apples to oranges but my 2014 F550 runs 12 hours a day. A busy day I might run 250 kilometers. The rest of the time, it idles. Never had any kind of emissions issues whatsoever. Even now that we're starting to work the bugs out of the new Tier 4 construction equipment we're not seeing many emissions related issues, even in the cold.