I spent a fair bit of time in Kensington n Chelsea last year and it's the most F10 535i/d I've ever encountered (still not common). But they were usually in colours like Beige and in SE spec. I'd hazard a guess at the owners being fairly wealthy and not caring about M Sport spec or resale values.
Is there a bigger difference in cost when new compared to the E60 535d and the F10? Because there's plentiful E60 535d's but F10 is still a rare occurrence. It's been about 6 years since release I would have expected more?
Almost every F10 is a 520d. The 6 cylinder diesels are pretty rare. It's a real shame and makes it hard to find one to buy! Both of mine took months of searching.