The other week I had to yank my sons 1999 turbodiesel out of the snow so I used a tow rope attached to the rear of my 07 ML CDI.
As I was down on my knees attaching the rope I had my face right on the tailpape. I was really surprised how undiesel like the exhaust smell really was. It was almost a sweet smell.
I guess going from 500 ppm down to 15 ppm sulfer really cleaned thing up.
Wonder if the commen rail direct injection techniques help clean up the combustion too?