An in-depth used car report claims that the average value of three-year-old executive cars plummeted by 21.3% in the year to January, while family cars such as the Ford Mondeo, Vauxhall Vectra and Peugeot 406, dived 15.6%.
Research by the Alliance and Leicester Used Car Price Index claimed that the 'transaction value' of a three-year-old Vauxhall Omega had fallen from £7,500 to £6,400, down 15%, while a Saab 9-5 fell from £14,800 to £12,050 (down 19%) in the same period.
It also claimed the Vauxhall Vectra sale price had collapsed from £5,475 to £4,975 (down 9%) over the same period, while the Renault Laguna has plummeted from £6,300 to £4,250 (down 33%).
But as the figures were released, Adrian Rushmore, managing editor at Glass's Information Services, raised concern about the claims in the report and the potential impact on the used car market.
He said: 'Drops of this magnitude would be awful. We are seeing falls, but not of this size. Movements have generally been a fall of between 3% and 8%, with an average of 5%. But if a particular sector fell by 21%, then that would be catastrophic. The movements we are recording are nowhere near that amount, or the 15.6% fall claimed for family cars. The impact of these sensational claims does not help.'
The A&L Car Price Index is based on the best-selling models in eight categories, using mystery shoppers and price guides from What Car? It is combined into an index for each category and figures are weighted according to the volume of sales for each model.
Douglas McWilliams, of the Centre for Economics and Business Research, which independently audits the figures, defended the Alliance & Leicester report.
He said: 'The stock market has dropped 50%, so it is possible that the price of used cars might fall by 20%, particularly because of increased supply from growing new car sales. I believe our data has been more accurate than other providers during previous audits and there have been strong negative year-on-year falls.'
Price index for three year old cars
Category - RV change
City cars: -9.4%
Small cars: -3.4%
Family cars: -15.6%
Compact executives 5.7%
Executive cars -21.3%
Luxury cars 2.3%