I've got the 140 Tdi.
Stop/Start traffic driving is usually 38 - 44
Motorway Driving is usually 46 - 50
A roads / rural driving 50 - 56
The 170 is only going to be marginally less than the 140 & having driven a 170 Scirocco, given the choice it'd be the 170 for me next time
DPF's can cause issues from what ive read and are expensive to replace so i'd have it removed!