My 520d Touring has been 100% reliable over 9 years / 65,000 miles from new - just needed routine servicing and a battery. I've been planning to replace it with a new 520d Touring but worry that diesel cars may become undesirable and suffer significantly higher depreciation than petrol cars.

Fears over diesel pollution are increasing, so might fuel duty and road fund licence on diesel cars increase disproportionately? Might diesel cars be penalised in city centres? If so, a 528i might make more sense.