Funny isn't it. My trusty 1997 300tdi Defender will do 30mpg all day long (although not over 65mph!) and that has plenty of extra weight fitted from the off roading options catalogue, all terrain tyres and a full roof rack! It also tows very well.
My 2018 Navara, doesn't tow anywhere near as stable, especially at full weight, but is much nicer to drive day to day!. It returns 35-40mpg on a run with all the tools in the back and on all terrain tyres!
Nothing that you can buy today seems to get anywhere close on fuel consumption. Pickups or Defender... Where did we go wrong?
You know I had an 08 fiesta zetec s diesel years ago. Brilliant little car, basically an ST spec with a diesel in it, 1.6l I think it was. I played with it a bit obviously so I didn't get left behind with mates who had the 2l petrol ST or Saxo vts

But that car returned north of 60mpg everywhere you went and at whatever speed. Now the idea of DPS's and Adblue is to remove particles from the air and reduce Nox emissions right?
So my question is this...
If a car burning diesel so efficiently that it will do 60mpg or more but with no stage 4/5/6 emissions control fitted. What is the difference in particulates between that and one with a DPF/adblue fitted returning less MPG because of it.
My gut feeling is on a comparable fiesta there's probably not much reduction in MPG due to euro 6 on the modern ones - I don't know, I haven't driven one. But on a bigger vehicle, say a lorry? I wonder?
Could someone build an engine that burns so clean it doesn't need a DPF to meet the figures (of course it would need a DPF by law) but my point is, it might be possible? Especially with better quality fuel - I think that's half our issue with MPG figures these days - the fuel is crap!
Food for thought on a Sunday.