Research for CAP Black Book Live has revealed weakening used car trade values during November as supply increases and dealers become more cautious.

However, prices for three-year-old stock - the cars at the heart of the fleet sector - are depreciating more slowly than the overall market.

CAP's message to fleets is not to expect too much of a downturn in values over the next few months. And figures from BCA and Manhein for October reveal ex-fleet stock has hit record values since they began measuring the figures (click here for more).

"Traditional fleet stuff is so thin on the ground – and still so desirable – that it’s virtually immune from accelerated depreciation at the moment," said CAP spokesman Mike Hind.

"The main issue is that so much is now being defleeted at around 40 months with 70,000+ miles, which means that the core 36-month/60,000 sector is under-served in the used market."

Despite the more positive position for ex-fleet cars, CAP reports that the 'auction buzz' - its internal  measure of the mood at sales - reveals a downward trend. And dealers' perception of the desirability of stock on offer is also taking a tumble.

This has resulted in reduced demand and lower bids, resulting in falling values for the used market as a whole.

However, CAP points out to the on-going strength of prices compared to historical performance. Last year underlying values fell between September and November by 2.8%. This year the reduction over the same period was 1.5%.

One of the key dynamics that has led to the relatively low depreciation of cars this year has been the maintenance of stable retail demand. An index forming part of the Black Book Live research process measures dealer perceptions of customer appetite for their cars and subsequent sales activity. This measure has remained consistent since the measure was introduced in June.

Hind said: "Black Book Live users are now seeing values reducing on a daily basis, in contrast to the months of stability earlier in the year. This is driven by the increase in supply from sources such as dealer part-exchanges which have remained unsold or which were never suitable for retail.

"Our measures of the mood at auction and dealer perceptions of stock offered in the open market are a perfect illustration of the underlying dynamic of the current market.

"Not all values are falling, however, and there are real opportunities for anyone with their finger on the daily pulse of the market to make some quick trade purchase or disposal wins even as the market slows. The key is knowing which way individual model values are moving, which is where Black Book Live users have an advantage over those who stick with a traditional monthly guide".