Despite being labelled as performance-enhancing, super fuels bring few gains in terms of engine efficiency, Which? has found.
Accordingly, the group has advised consumers to opt for standard petrol at the pump to avoid forking out money unnecessarily.
In one case, the group found that a super-fuel offered by Tesco actually decreased the engine power of a 1.6 litre Ford Focus.
Meanwhile, super-fuel testing on a Volkswagen Golf showed little improvement over standard petrol performance.
In addition, claims that the fuels were better for the environment were also found to hold little weight, with only marginal reductions in pollutants noted.
Richard Headland, editor of Which? Car, commented: "There's no conclusive evidence to show that super fuels are better for your car in the long run - so in a time of high oil prices, why would you choose to pay more?"
In other recent research, the consumer group found that in reliability tests, Japanese models took the top seven slots in its annual survey.
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