Fleet cars that have no V5 documents are almost impossible to sell on the used car market as buyers become increasingly intolerant of cars without a full set of paperwork.

Nearly half of all dealers buying used cars for stock now have policies in place of not acquiring a car, even from a reliable and reputable source they would usually use, without a V5, even though getting a replacement is a fairly straightforward process.

And research by CAP has found that the rest of the trade buys cars without V5s only at substantially lower prices.

The cost of a replacement document is £25 – having gone up in May from £19 – but CAP has found that buyers are paying between £200-£500 below market value, citing the inconvenience of obtaining one as the major factor.

Since 2003, all cars have needed their V5 in order to be taxed, and many service companies are now offering fleets storage facilities for important documents.

But it is not only a vehicle’s V5 that is integral to the price achieved at disposal.

CAP has also discovered that two-thirds of dealers will factor in up to £400 for a car that is due an MoT, although the vast majority are not actually deterred from buying the vehicle.

Robert Hester, of Black Book’s research team, said: “This is yet more evidence of the importance of presenting cars for disposal in the right way.

“Dealers are under huge pressure to turn their stock around quickly, which generally means, under normal market conditions, they will avoid buying work wherever possible.

“The fact that they will still buy a three-year-old vehicle without an MoT or with the V5 missing should not be taken as a green light for not ensuring that they do not have to.

“All that will happen when cars are not presented correctly is that the disposer will pay for the inconvenience to the dealer of replacing missing documents or risking costly workshop time.

“Dealers are canny and will do whatever they can to pass on costs – or even the risk of costs – and the easiest way to do that is by paying as little as possible in the first place.”