Average used car selling prices were down by 1.7%, or £103 to £6,068 in August compared to July, according to the latest monthly analysis from Manheim.
The fall compares with a much larger 6.3% (£413) month-on-month fall in July.
August analysis also shows that conversion rates have improved slightly - the first month-on-month improvement since February.
While the average month-on-month selling price in the majority of vehicle segments within each of the fleet, dealer and manufacturer sectors decreased, there were some exceptions.
In the fleet sector the average selling price of medium family vehicles increased by 2.1% (£102) and the SUV sector increased by 1.4% (£127).
In both fleet and dealer sectors, average values fell less than during the previous month but values in the manufacturing sector saw a steeper decline than reported in July.
In the fleet sector average month-on-month values fell by 2.1% (£106) compared with a fall of 8.0% (£444) in July, while in the dealer sector average month-on-month values fell by 3.7% (£67) compared with a fall of 5.6% (£106) in the previous month.
The manufacturing sector saw a further month-on-month drop of 2.2% (£234) compared with a fall of just 0.8% (£84) in July.
Mike Pilkington, managing director, Manheim auctions & remarketing, said: “The August market is traditionally a quieter month for wholesale activity and although there are more positive signs than have been evident in recent months, caution must be exercised in drawing too many conclusions about market stability from one month’s figures.”