Used car prices are set to tumble from September 1 as dealers push out stock to make way for a glut of 'old-plate' nearly new vehicles.

The wave of late, low-mileage cars for disposal will come in the wake of a retail and fleet buying rush to be first on the block with the new style registrations, industry experts predict.

According to auction group Manheim Europe, the market is already feeling the effect of the September plate change.

Senior group auctioneer Andrew Shepherd said: “The franchise dealer buyers are aware that the new car registrations will provide them with an abundance of nearly new cars for retail and are, therefore, holding back in the auction halls.

“The remainder of July and August will be a difficult period in the disposal market.”

Mr Shepherd's fears were echoed by Cap Network's national research manager Martin Ward, who said: “There'll be a lot of used cars on the market from September and that volume will be reflected in a downward spiral in prices that may last well into October.

“Only the newer diesels are likely to be immune from the price squeeze, as they are still in very short supply.”

Bread and butter models with low mileage and high specification should still command a premium, according to Manheim Europe, whose message to those looking to shift stock before September was to “remain vigilant on the rostrum and wherever possible put cars on sale to give the buyers some incentive”.

Mr Shepherd warned: “Be very aware and alert with 100,000-mile-plus stock, as first bid may be the only bid at present.”