Question for Mark, how often does a diesel DPF need regen cycle?
Don't think emission zone extends that far, even new one for 2020
It depends on the way they are driven, could be weekly, could be monthly....
BUT all the diesels ive driven haven't had a DPF fail.....some of them you know when they doing a regen cycle....ie idle engine revs increase....the skoda VRS I had was a good example of that.....used to idle at 900-1000rpm when it was doing a regen cycle.
If it couldn't achieve the regen cycle.....it used to put on a warning light....generally a motorway run of 10miles in 4th gear (about 3500rpm) would make the warning light to go off

My Mondeo, ive no idea when its doing a regen cycle.....gives no clue.....but in the 6 months ive had it.....no warning light has come on about it.....and when I looked earlier today....my average speed is 17mph!

but average fuel consumption is 47.5mpg

You could of course go for a slightly older diesel.....57reg perhaps.....it probably wouldn't have a DPF, as I think that it was made law on 08 reg's or thereabouts......