The influence of fuel octane on fuel consumption

The Asian Clean Fuels Association (ACFA) and the European Fuel Oxygenates Association (EFOA) contracted Ricardo plc to conduct a study on fuel-octane effects on the fuel consumption of light-duty vehicles (LDVs). The study focuses on regulatory requirements for fuel economy or greenhouse gas (GHG) emissions, the LDV technology roadmap to meet those requirements, and the role of fuel octane in this future challenge.

Regulatory requirements for LDV fuel economy or greenhouse gas emissions are driving significant changes in how LDVs, especially their powertrains, are being designed. Ricardo‚Äôs technology roadmap suggests that internal-combustion engines will continue to play an important role in LDV powertrains, even as LDVs are increasingly electrified. Ricardo also sees an increasing role for fuels to contribute to an overall ‘wells to wheels’ GHG-reduction strategy.

From the literature review conducted for this study, the direct effect of increasing fuel octane on fuel consumption is limited, as octane only comes into play when an engine operates in a knock-limited regime. Most regulatory drive cycles are relatively gentle, although real-world driving can be more aggressive. With downsized engines being an important part of future engine design, though, operation in high-load, knock-limited regimes becomes more likely. That said, the main benefit of increasing the commonly available octane in fuels appears to be that it facilitates engine design changes, such as increases in compression ratio, that directly lead to improved fuel consumption.

Therefore, Ricardo expects fuel octane number, especially research octane number (RON), to be an important contributor to future GHG emissions reduction from LDVs in all markets.

Read the full report here: The influence of fuel octane on fuel consumption