A study by a British product information guide placed three "super" fuels up against cheaper alternatives, and found there was little point in using super fuels.

The study by the product information guide named "Which?" found that super fuels don't save money, improve a vehicle's performance, or help protect the environment.

Shell V-Power, one of the unleaded super fuels tested, gave a 1.6-liter Ford Focus a marginal power increase.

But filling the car on this fuel for 12,000 miles would cost more than using Shell's standard fuel.

And Tesco's Super Unleaded – another of the super fuels on test – actually decreased the Focus's power.

Which? also looked at the impact of super fuels on turbo- and supercharged engines.

The VW Golf's high-tech 1.4TSI engine responded well to Shell V-Power, but there was not much difference between super fuels and ordinary fuel when it came to economy and emissions.

BP Ultimate diesel – the only diesel super fuel on test – actually made the fuel economy and performance of a Renault Mégane 1.5 slightly worse.

The study said motorists would do better to drive less frequently and more economically if they want to protect the environment, as the super fuels tested only had a marginal effect on emissions and pollutants.

Super fuels may offer some long-term benefit, as they include detergents to improve engine longevity. But Which? Car said any break-even point in terms of reduced repair bills could take many years to reach.