India has switched over to the world’s cleanest petrol and diesel without raising prices, Indian Oil Corp (IOC), the nation’s largest oil firm, said on Thursday. Leapfrogging from BS-IV grade fuel straight to BS-VI grade, equivalent to Euro-VI fuel, petrol and diesel would have resulted in an up to Re 1 per litre increase in cost but oil companies decided against passing this on to consumers and instead adjusted it against the reduction warranted from international oil prices plummeting to a 17-year low.