I stumbled across a couple of issues which seem to do the rounds on various forums, so I thought I'd ask here for a definite answer. One is that the Start-Stop mechanism, as implemented in the Audi A6 2.0 Ultra S Tronic, is having an impact on the regeneration process overall, in ways which could impact the aftertreatment system in the long run. Also, the use of the Shell V-Power diesel - which personally I find fantastic - with its propensity to make the engine run at lower revs in the S Tronic, make it more difficult to achieve the higher temperature required for active regeneration, with long-term effects on the health of the aftertreatment system.