Black Book Live senior editor, Derren Martin said: ‘Self-registrations remain a feature of the market because of an insatiable desire by many manufacturers to maintain or improve their market share.

‘Anecdotal evidence is suggesting that self -registrations are accounting for around 20% of monthly reported registration totals.  However, we are not seeing any discernable negative influence on the values of late-plate used cars.

‘It may be that this activity is now so well established that the relationship between prices of new and late used has reached equilibrium.’

CAP added that its Black Book Live has observed that the reduction in total volume caused by the 2008/09 slump in registrations is now helping to prevent oversupply. Despite an increase in supply this year, overall numbers are still down on pre-recession levels.

Auction conversion rates typically increased by around 10% during May, compared with the end of April, although the determination of some fleet vendors to hold out for higher prices has been resisted by dealers who are equally determined to pay prime prices for only the highest quality cars.

‘What is interesting is that the number of cars being sold at the traditional three-year point has decreased fairly dramatically over this period,’ explained Martin.

‘In 2008, 20% of cars sold were between 2.5 and 3.5 years old but in 2014 that percentage has fallen to 13%. Conversely, six years ago around one-third of sold cars were over six years old while now the figure is more than half.

‘Businesses and consumers alike have clearly been holding onto cars longer during austere times.’