The European Union has been urged to launch a probe into the rocketing price of petrol.
According to the Federation Nationale de l'Automobile (FIA), the method used to determine prices is "far from transparent". The association represents 35 million motorists.
The coalition of motoring organisations, whose members include the AA and the RAC, has written to the EU demanding an inquiry into how benchmark prices are set at Europe's key trading centre, the Rotterdam spot market.
Last month UK petrol prices reached record levels, driven by an increase in wholesale oil prices. However, petrol prices did not fall back as quickly as the crude price dropped.
Currently, a full tank for an average European car costs over £10 more than it did a year ago.
Werner Krauss, chairman of the FIA Eurocouncil, said in the letter that "a platform with such a small volume is doubted to be a representative indicator for the vast European market".
Mr Krauss also wants the EU to look into the role of speculation on oil prices, adding that the FIA is very concerned about the "resulting volatility in fuel prices and negative financial impact on consumers".
Luke Bosdet, of the AA, said "No one is giving us any answers as to why petrol prices are so high. We need greater transparency so that everyone can see we are paying a fair price for fuel".
The AA wants to see an independent regulator to balance the interests of the supplier, retailer and customer.
The British Petrol Retailer's Association, which represents 6,000 petrol station owners, also expressed concern about the issue of transparency. It is to press the UK Office of Fair Trading to look into whether its members are getting a fair deal.
© Press Association 2011