Managed 49mpg tonight on a 35 mile round trip consisting of 4 shorter journeys, mainly at 70mph. 2 sets of regens were going on - the second leg of 9 miles on a fully warm engine, and the third leg, around 11 miles, also on a warm engine. Temps up to 98C on the second leg, settled down to 95C when I reached the mother-in-law's house and the fans were blaring. Third leg was happy to sit at 95/96C, the odd stoppage at lights with 1000rpm idling and non-availability of stop-start on the third leg confirmed regen was still happening. I was in the early 50s on the second leg, the third dropped it to 49 and it stayed there for the rest of the journey.
The biggest difference between this car and the Scirocco seems to be it's reluctance to run warm generally and be passively regenning all the time. The GTD seems to want to regen in batches, presumably to keep official CO2 and NOx emissions lower on the tests e.g. rather than doing 120g CO2/Km all the time, it would rather have 80% running on something like 109g and 20% (when regenning) running on something like 130g CO2/Km - ensuring that regens don't occur during cycle testing. Running a little cooler reduces NOx emissions, and the limits of NOx emissions for diesel cars have reduced a lot from Euro 5 to Euro 6 standards.
It all seems a bit of a "pull the wool over your eyes" exercise as far as CO2 emissions testing goes. The car isn't combusting diesel any more efficiently to reduce soot compared to the previous gen, VW just ensure that they perform their emissions tests on an empty DPF.
