BCA saw the average price of fleet cars fall by more than £300 in May to £6,986 – down on the monthly record average value of £7,299 set in April.
Manheim’s results showed values eased back by an average of £70 to £5,844.
May’s market saw average mileages rise – BCA seeing an average of 59,466, up from 58,208 in April, and Manheim’s rose from 50,432 to 51,276.
BCA’s communications director, Tony Gannon, said: “Competition for the best ready-to-retail cars is keeping values at almost artificially high levels but this conceals the rising number of unsold cars where over-optimistic reserve prices have put them out of the reach of buyers.”
Manheim’s group communications director Rob Barr added: “Overall the market is clearly easing off, but nevertheless the demand is still there for the right stock.”