After owning e60525d automatic for nearly a year...I have concluded its for those that spend atleast 60-70% of their time on dual carriageways and motorways...
on motorway better all round mpg (45mpg plus), insides of fuel system/exhaust etc kept clean(er)
stop/start city...expect very low mpg (low to mid 20s max), high mtce on various compenents of fuel/exhaust setup.

I would recommend the 320d e46 which I also have/had and mpg was 45 mpg all round and need for more mtce on various parts was no way near the 525d.

But above all for reliability/mtce free motoring no frills...the japanese