No one can argue that turbo diesel engines are less reliable than their non-turbo equivalents, are more expensive to buy and maintain, are more complicated, are more highly stressed and as a result suffer more engine (as well as turbo) failures, and modern non-turbo gasoline engines are now the most reliable engine and easily do equivalent mileages (many 100,000's) without problems, they are cheaper to buy, the engines are lighter, they warm up quicker. Just when we have got petrol engines to this peak of efficiency and superb reliability we are going down the same route that causes problems in Diesels. As I said before a Diesel runs on volumes of air, the more you can push in the better, and they can run lean, and Diesel fuel is about 15% more energy dense than petrol, which accounts for some of the extra mpg from a Diesel. A petrol engine has an ideal maximum air / fuel mix of 14.7:1 and no more, the extra heat generated in turbo petrol engines has to be got rid of, reducing thermal efficiency, also to cool combustion a richer mixture ( lower air / fuel ratio) is used - using more petrol. When you add all the plumbing and extra electronics and sensors required it is a complication with little or no benefit, and significant downsides. Car manufacturers like any other business are subject to fashions, if other people are using technology that promises 120mpg and 150BHP from a 600cc engine then other feel they have to do the same, it takes a while for the truth to come out about reliability and servicing costs, and also that the efficiency gains are not always what they seem, and when manufacturers test their engines they will always do it in the most advantageous way, after all who sits at 50mph on the motorway all day, car engines operate over a wide band from chugging around town to blasting down the autobahn, and no one technology can offer efficiency gains across this whole spectrum. Remember the old saying 'if something seems too good to be true, it probably is'