Hi
I`ve just read this thread and if you do not mind I`d like to elaborate a little on the consumption.
On a big 1400kg car with a Cd of around 0.31, the 240Nm and 110HP engine will struggle even in a normal setup, thus adding DPF will only make it worse. Improving aero would of course help, but not so much in congested traffic.
If you are up to it, I would advise a good remap. It lowers the consumption and makes the car more comfortable to drive because acceleration is more effortless.
For instance, check out this video from 2:30 onwards and see the difference a remap can make even at a steady speed.
Keep in mind that the 725tds weighs a lot and needs more power, but you can get the idea.