BMW build better diesel engines. Its that simple
Never understood eco modes / maps etc. as said you just end up driving harder. When people ask me about eco remaps I tell them that they are next to useless; hence why I only offer something towards the more performance orientated end of the scale. It obviously works as most report at least a 5mpg improvement

My own personal experience with the PD engine (yes its old tech) in my Audi is that its a lot happier sat at motorway + cruising speeds than tootling around A&B roads
Oh and to get it even close to the quoted MPG figures its taken DPF delete and remapping........