I think my XR6 Ute was one of those but inside was fineOur pre dpf 2007 1.6T HDI C4 does not stink at all. I've followed it closely in my DS, no detectable fumes at all.
However, those rotten egg petrol stinkers, that lay down a trail as they try to accelerate past..... they are the worst.
Even idling odour was offensive, but nothing like my parents old 300D idling in the garage, guess who had to open the roll a door behind the tailpipe, being the youngest slave, I mean child.