In a Statement of Objections the OFT highlighted five separate alleged infringements that took place between March 2007 and January 2010.

Each alleged infringement involved up to three dealers and the OFT claimed evidence also suggested the manufacturer was involved in two of the cases by helping to facilitate or consolidate the arrangements between dealers.

The OFT said the alleged infringements involved elements of market sharing, price fixing and exchange of commercially sensitive information.

Ali Nikpay, OFT senior director of cartels, said: “We have reason to believe these dealers co-operated to limit competition in their areas.”

He said the case concerned dealers operating in the north of England, Wales and Scotland and claimed it showed “the OFT’s commitment to pursuing allegations of serious competition law infringements irrespective of the size of the companies involved”.

The consumer watchdog stressed that its findings were provisional and that all parties would have a chance to respond before it made a final decision as to whether competition law had been infringed.

The Statement of Objections was addressed to the following companies – Cicely Commercials, Enza Motors, H&L Garages, Northside Truck and Van, Road Range and Mercedes-Benz UK.

In a statement Mercedes-Benz UK said: “We now have detailed information about the investigation of the OFT for the first time. We will analyse the information and then give our feedback to the OFT. Please understand that we cannot comment further in an ongoing procedure and we will continue to co-operate with the authorities.”