The latest price data shows that average prices for used cars continued to rise in the third quarter.

However, September was relatively weaker than both 2006 and 2005, and there are concerns that values could come under pressure in the final quarter of 2007.

Accoding to BCA, values for fleet and lease vehicles rose to £7,345 in September, an increase of nearly £400 over August.

In comparison, last year values leapt by nearly £1,000 between August and September.

Against CAP Clean values averaged 98.4% - the highest figure recorded this year - although CAP percentages did not hit the heights they achieved in September 2005 and 2006.

Values in other sectors also reached record levels in September. Part-exchange values peaked at £3,280 – a modest rise of £40 over August, but still the highest monthly value on record.

While third quarter values have been strong this year, they could be concealing a weakening market. September has not provided the step up it did in 2006, and the signs are that values will be under pressure in October and potentially to the end of the year,” BCA’s communications director, Tony Gannon, said.

“In September last year, fleet values reached record levels at £7,190 and the leap from August ‘06 to September ‘06 was nearly £1,000. This year, record values have again been achieved but the increase over August was less than £400.”