New car buyers have missed out on discounts worth £250 million to which they were entitled, it was claimed this week.
Oliver Prill, managing director of Jamjar.com, the car-buying website, claimed about 50% of car buyers did not get the discounts they should have accessed since the launch of the Supply of New Cars Order 2000.
The order was intended to level the playing field between fleet and private buyers by giving dealerships access to the same buying terms as companies.
But Prill said: 'The fact is that today, discounts and car prices remain very different in the retail and fleet market. The knock-on effect is that half of all retail buyers are losing out on up to £500 a car.'
Several dealerships have already made complaints to the Office of Fair Trading. A spokesman said on Monday it was investigating the complaints, although it could not give a definite answer on when it would reach any conclusions.
But a spokesman for the Society of Motor Manufacturers and Traders condemned the attacks as unjustified, claiming they would just damage confidence among buyers and harm consumers, fleets and manufacturers alike.
Last year, at the height of the previous OFT investigation, residual values reached new lows as buyers stayed away until certainty returned to the car market. Only in the past few months has the market made a visible recovery.
The SMMT spokesman said: 'If there was any evidence to justify these claims, then the dealerships involved should make their comments public. The Office of Fair Trading has to investigate all complaints, whether justified or not. Do not expect anything to come from it, because the manufacturers have their house in order.'