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Fuel additives

Do fuel additives add up?

Fuel additives may sound tempting, but do they really work? Which? put a selection of 'miracle' car fuel boosters for both petrol and diesel engines to the test to see whether their claims can be justified.

Fuel additives

In our full report you can see...

    • Verdict on fuel additives

      Fuel additives claiming to increase your car's power or fuel economy sound tempting - but can they live up to the hype? Which? finds out.
    • Petrol fuel additives compared

      Find out how five petrol fuel additives - from brands such as Redex and STP - performed in our lab tests, and whether they're worth the money.
    • Diesel fuel additives compared

      Our lab tests the claims made for four diesel fuel additives - from Millers, PD-5, Redex and Wynn's. Which - if any - are cost effective?

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