The OFT has been investigating claims that under the Supply of New Cars Order 2000, carmakers were not offering dealers similar discounts on volume deals as those obtained by fleets.
It concluded that none of the manufacturers investigated had “discriminated unjustifiably” between fleet customers and dealers.
Dealers, it added, were offered “at least the equivalent of the average fleet customer discount for a particular model after all the benefits had been taken into account”.
Alan Pulham, RMI franchised dealer director, said the association was disappointed with the outcome.
He added: “One area of the OFT's response that we are particularly concerned by is the fact that the OFT has made a statement about the review of Block Exemption at this crucial time, when the European Commission is drafting its new policy.”
John Vickers, director general of Fair Trading, said he was “concerned that unexplained EU price differential existed”.
“We believe major changes are necessary to Block Exemption to ensure the UK market for new cars works better for consumers,” he said.
The SMMT welcomed the OFT's findings.
Christopher Macgowan, SMMT chief executive, said: “The investigation proves that the market is operating in a competitive and fair way and we are delighted that the OFT has made this view public.”