Interesting. I was in the mountains at 4-6k over the weekend, and even once fully warmed, I get the smoke when in gear, on the gas, coming down hill (low range). I suspect that a worn, even if good condition, engine will smoke, but a new one won't? Slight compression values make the difference?
Well, I was moderately loaded down for the trip, and I stayed between 50 and 60 mph on the passes. In fact, the vehicles ahead of me often had more to do with weather I needed to shift down to 4th or could stay at 55-60. Only once did I need to shift down to stop the EGTs from going past 1250. That said, a friend of mine with a heavier 110 300Tdi did the same thing, and still gets 24 mpg, which I cannot come close to.