FPInnovations helps us find the answer to this question.Performance Innovation Transport (PIT), an FPInnovations group, carried out efficiency testing of a premium diesel fuel, Shell Diesel Extra, during 2013. Four 2009 Freightliner trucks were used for the test. They pulled a 16 m (53 ft) semi-trailer around a high-speed test track. The fuel consumption was measured by having one set of trucks using the premium diesel and the other on regular diesel. The trucks also used these fuels during their regular operation for some months before the test. The results showed fuel savings of 2.4% when using the premium diesel compared to the regular diesel. The use of the premium fuel also reduced emissions by up to 2.06 tonnes per truck. Source: http://pit.fpinnovations.ca/Pages/home.aspx