mileage - you get more mileage out of the diesel than petrol per tank even with x-drive feature on the diesel that consumes a bit more than RWD. 750km avg per tank mostly city driving 80% and highway driving of 20% (odo only clocked in about 2000kms to date, gets slightly better with more mileage clocked in).
clatter (cool to me, not to some) - you get the all too familiar diesel clatter (love it or hate it) which is quite audible when you drive along objects that deflects the clattering noise from the engine through the wheel arch and into the cabin, such as highway concrete divider, car, enclosed area like car parks. if you can live past that, the diesel will serve you very well.
torque - you get addictive torque pull when you need it during normal overtaking maneuvres.
x-drive = heavier steering - x-drive makes the steering noticebly heavier than the petrol. haven't had the chance to put the x-drive to test off roading or slippery roads.
better specs - locally, they speced the diesel slightly better. x-line trim, sat-nav, bigger idrive screen, dvd ent. system, 18" wheels, paddle shifters to name a few.
on the downside, you get the same below par finishing on both diesel or petrol with some hard plastics used on the dashboard meter cover, that results in some un-BMW like tiny rattles on the dash and from the trunk. some people complain about the firmness of the suspension but that gives me a bit more confident on the highway with speeds over 140.