I have a BMW 730D which gives around 33 mpg overall.
I sometimes think that the current range of common-rail diesels are an engine problem looking for somewhere to happen.
Many do huge mileages, but then you look on the owners web-sites for a particular model, and find all sorts of potential issues which could scrap the car.
The Delphi diesel pump can fail on Ford, Vauxhall, Renault, Citroen, etc., and cause damage of around £2500, the BMW diesels can have timing chain issues, turbo failures (c.£1500 to fix) and swirl flap failures. Audi/VW also have their issues and my son's Audi 2.5 estate diesel had a timing belt sprocket bearing fail and the damage cost him £3000 to have fixed.
If any of that sort of random failure happens it would possibly scrap the car and then a petrol version would have been cheaper.
One might wonder if the very long oil service intervals (like 18,000 miles) are a good idea on a diesel with the dirty oil feeding the turbo and timing chains. I'm changing my oil early and doing it tomorrow, but using the approved fully synthetic oil will cost over £90 for the oil alone, plus the filter. Still, it's cheaper than scrapping an engine. I removed the swirl flaps 3 weeks ago and fitted blanking plugs.
Edited by Cooperman, 29 July 2013 - 11:50 AM.