The decision by Mercedes-Benz not to export its latest supercharged CGI direct injection petrol engine to the UK had an oddly familiar ring to it, provoking thoughts of headlines condemning UK 'dirty fuel'. We've been here before of course. When Mitsubishi wanted to introduce its GDI direct injection petrol engine a few years ago, it had to be reworked to cope with the higher sulphur content of European and UK petrol. Anthony Lewis reports