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Hi there - just wondering whether there is any significant difference between each of our fuel retailers and the fuel products they sell at their sites? More so, are the fuel products (say 91 Octane) between retailers different enough to conclude that fuel economy is better by purchasing fuel from one retailer as opposed to another? I've seen on the retailer's websites that some contain "additives" in their 91 Octane, especially Caltex who say their fuel contains Techron, however given NZ's strict standards for fuel sold in NZ, are these true? If you could shed some light that would be great.

P.S. I drive a petrol driven 2009 Hyundai i30 and use 91 Octane - I tend to fill up at Mobil as my fuel card provides me the best cpl saving here.

Essentially all the fuels sold in NZ are identical (except for octane rating) as they must meet the same strict fuel quality standards. The exception is Gull’s 98 octane which contains 10% ethanol. In fact half of all the petrol sold in NZ even comes from the same source – Marsden Point refinery – regardless of retail brand. All brands add their own additives to their petrol – usually only premium octane – which are detergents that are claimed to improve engine performance and economy. The AA has not tested the validity of these claims, but we have seen some fuel company test reports that show very small fuel economy improvements. Any benefit to engine longevity from using additives won’t be noticed in the short or medium term. These additives are optional, but fundamentally do not affect the fuel quality or octane rating.

By way of comparison, for a car that is designed to run on 91 octane, there would be no economic benefit using 95 octane just because it has additives, as the additional price would more than outweigh any potential benefit. Similarly, there would be no economic benefit in paying more for 91 with additives if you can buy another brand without the additive for less.