Petrol is a complex mixture of different chemical compounds that must comply with a set of strict specifications. One key parameter, indicating the fuel performance in an engine, is the octane number. The octane number measures how good a petrol is at resisting to premature detonation in the combustion chamber of an internal-combustion engine (knocking). Engine knock can lead to severe engine failure. The so-called Research Octane Number (RON), that simulates fuel performance under low speed and low severity engine operation, is most relevant for modern engines.
In Europe, the majority of petrol sales consists of fuels with a petrol grade of RON 95. They accounted for 86,3% of the total petrol fuel sales in 2016. In 2016, 7,6% of the fuels sold had a RON between 95 and 98 and 5,8% a RON over 98.
The EU made the commitment to cut CO2 emissions from non-ETS sectors by 2030 by 30%. Liquid fuels are expected to still represent 93% of all energy used in transport by 2030. Therefore, the EU needs to use all means at its disposal to reduce the carbon footprint of existing technologies. One of the options is to raise the octane number of petrol to RON 102.
Promoting higher quality fuels in order to reduce fuel consumption can be beneficial both to consumers and to refiners and car manufacturers. Consumers can drive longer on the same tank, while refiners and car manufacturers can reduce their CO2 emissions in a cost effective way. To achieve these significant improvements, legislators simply need to adapt the Fuel Quality Directive and the CO2 targets for car legislation
Higher quality fuels would provide an energy saving of at least 7% and 20 million less tons of CO2 from petrol engine cars annually, while also improving air quality.
According to a Society of Automotive Engineers’ study, increasing the octane number of petrol can result in reducing fuel consumption of at least 7% . When combined with a small changes to the engine, the octane number increase could reduce CO2 emissions by 20 million tonnes per year from petrol engine vehicles.
Higher octane also means a reduction of some of the pollutants (volatile organic compounds such as benzene and particulate matter) that have a direct impact on Europeans’ health today. In fact, a 7% of efficiency savings would equal a 7% reduction of exhaust and fugitive emissions.
Although higher octane is not the only solution to cut CO2 from road transport, it is one of the most cost effective, technology-neutral, and readily available to reach climate and energy goals by 2030.
 IEA: Fuel quality in the EU in 2016. Fuel quality monitoring under the Fuel Quality Directive
 E4Tech Study
 CO2 Emission Reduction Synergies of Advanced Engine Design and Fuel Octane Number, Ben Leach, Richard Pearson, Rana Ali and John Williams of BP International Ltd, SAE technical paper No. 2014-01-2610
 According to the study of the Society of Automotive Engineers, increasing the octane number of petrol can result in an efficiency saving of at least 4% to up to 30%. We take a conservative and illustrative 7%.