Fuels such as 95 or 98 RON (Research Octane Number) have a higher resistance to burn, which indicates higher levels of energy available for the vehicle’s engine.

According to NRMA motoring expert Jack Haley, on average, 95 RON can provide around 4 percent lower fuel consumption compared to 91 RON, assuming the engine computer adjusts to take advantage of the octane difference.

Using 98 RON might result in a 3 percent reduction in fuel consumption over 95 RON, again assuming the engine computer adjusts the engine parameters accordingly.

But fuelling an engine with 95 or 98 RON won’t necessarily lead to earth-shattering performance or extreme fuel economy if the engine is not specifically designed to run on it.

Premium grade fuels simply optimize an engine’s ability to produce power through increased fuel density, offering a more controlled burn, which reduces engine ping (detonation) and results in a smoother power delivery.

These fuels also contain detergents and boosters that help keep components such as valves, pistons, and combustion components free from surface varnishes and carbon build-up, which may help promote a longer service life.