DISPOSAL specialists are warning of a growing gap between the residual values of normally aspirated and turbocharged diesel cars. As more and more diesels flood back to the market following the diesel boom of the early '90s, used car buyers are becoming increasingly discriminating. With more choice available, three to four-year-old high mileage oil-burners are being overlooked in favour of the improved performance offered by turbodiesels.

Managing director of Cars Direct Roger Woodward said the situation was reaching oversupply as large numbers of diesel cars purchased by fleets during the sharp upturn in demand came back to the market. He said the average price difference between turbo and non-turbo models was around 5%.

A different view was taken by Chris Hesketh, manager of British Car Auctions' Brighouse Centre, who said: 'The latest generation of turbo diesels have gained a strong following. However, we have not seen a decline in demand for normally aspirated diesel cars.'

Glass's Guide editor in chief Arnie Fenn said: 'We are finding normally aspirated diesels are very hard work but turbodiesels are performing as they always have.' CAP chief economist Mark Cowling said the situation was more a case of fleets failing to realise the premiums for normally aspirated diesels they could have expected three years ago.