They warn the problem is affecting fast-cycle fleets, with traditional companies that keep cars for three-years relatively unaffected by growing plate confusion.
According to CAP Black Book, the three-year-old used car sector is this year revealing itself to be apparently immune to the issues at the newer end of the market, brought about by the proliferation of different plates under the twice-yearly registration system introduced three years ago.
Dealers are struggling with a growing array of numberplates that have been introduced in relatively few years, since 2000.
Tony Styles, senior editor of Black Book said: 'No wonder dealers and customers are confused. At the top end, customer perception is driven by manufacturers offering ever higher value. This may not be a problem in itself but the big questions arise just below this tier of the market. There are now 11 plates out there covering cars over a three year period – from 2000W to 2003 02 – in a market which dictates that each must have its own value.
'How exactly does the dealer and the customer agree on the value of the next car down the line when new cars are becoming more affordable by the week?'
But although there are significant issues causing some concern and confusion at the newer end of the market the typical three-year-old car remains apparently immune to these, CAP claims.
Styles added: 'Hidden behind this issue is some very good news for the market as a whole. When you look beyond the recent multi-plate confusion there is a far more settled three-year-old market. Here the concertina effect comes to a halt and values remain firm. This has been repeatedly demonstrated throughout the early months of this year and bodes well for the long term health of that all-important core of the UK used car market.'