The Saab doesn't like winter diesel... I've seen the difference between summer and winter diesel in the past but in the 9-3, yeah you lose a little mpg, but it soots. Lots.
Actually it was great, the TiD was chucking out a great big cloud of black soot when trying hard, 'course most of the time it's cruising along on the motorway so not exactly working hard.
This week just gone I've tweaked *down* the tuning box. Now it's slower but doesn't soot as much. Anywhere near as much.
Mind you I could tweak the boost up higher and give it some Italian tuning...