Figures produced by the Society of Motor Manufacturers and Traders (SMMT) show sales of used cars for the second quarter of the year are 6.4% up compared to the same period last year to 1,955,398 units.
Tony Styles, senior editor of CAP Black Book, said: 'Feedback indicates that auctions have had fewer cars to sell. If sales are up then fleets may be using other routes to re-market. There has been an increase in the number of leasing companies using other more diverse markets.'
Industry experts say the market remains bullish for the year. Year-to-date used car sales total 3,916,738, up 10.8% from last year's figure of 3,534,246 units.
Vehicle Remarketing Solutions is one company which offers an alternative re-marketing route. The group is targeting a national network of dealers to re-market its vehicles using 'discreet remarketing'.
Mike Pilkington, managing director at Vehicle Remarketing Solutions, said: 'Fleet operators are increasingly looking for new ways to minimise the wholelife cost of a vehicle.
'Choosing the right route to market is one of the most effective ways of achieving premium prices for stock.
'When vehicles are competing in a busy market, discreet remarketing takes a rifle shot approach to targeting the best buyers.
'We are increasingly remarketing niche marques where finding the right buyer can make a difference of £1,000.'
Christopher Macgowan, chief executive at the SMMT, credits the increase in used car sales to increased new car sales.
He said: 'The upward trend in the used vehicle market continues to reflect buoyant new vehicle registrations.
'Used vehicle sales for the first half of the year have increased significantly on the same period in 2002.'
The SMMT counts cars, light and heavy commercial vehicles, motorbikes, special purpose vehicles, agricultural models, and buses and coaches as used vehicles when compiling its figures.