The trend has been noted by Manheim Auctions, which has applied a policy of withdrawing vehicles without V5s from sale, until the new paperwork is sent by the DVLA.
Martin Potter, Manheim Auctions' corporate sales director, said: 'This is very much in our customers' interests and we have worked hard with them to change internal procedures to minimise the negative effect on residual values.
'Either we flag up a vehicle without a V5 when it arrives at auction or we know where a vendor has already applied for the new paperwork from the DVLA.
'If we do not have the V5 within 10 days we constantly chase our customer until we get it.'
The company said vendors can lose out when the process of replacing new V5 documentation rolls over into a new month, with potential price reductions in the latest CAP and Glass's price guides.
Potter added: 'While this may downgrade the value of an average fleet car by up to a few hundred pounds, these instances are limited and it's essential to stick with the policy of waiting for the documentation before offering the vehicle for sale.
'Credit should be given to the DVLA which recognises the importance of this issue and whose strong relationships with major vendors mean new V5 documents are being replaced in just a few days.'