I was recommended by a BMW independent to avoid the 2 litre diesels due to big expensive problems with turbos and 100k is the most they go without issues so I'd avoid. Lots of stories on BMW forums of owners suffering big bills.

A family member had one and put Pirelli winter tyres on and it worked really well. It was 4wd not 2wd but the tyres made the difference not the 4wd. They used to get mid 40s with mixed driving. It was a 2008 MY and an auto.

Spiritmonitor de- a European vehicle economy database gives 35.5mpg average on a sample size of 104.

If running costs are key, would have thought there's far less risky and cheaper to run options than a high miler diesel BMW. Tyres on a 4wd will cost you don't forget, plus all the extra weight you're lugging around. Getting to work will depend more on traffic and gridlock than your particular vehicle.