Findings using CAPcalc, the small fleet revaluation software which analyses errors on fleet databases, showed that single keystroke mistakes can alter vehicle values and affect a whole fleet portfolio.
Examples of errors found by CAPcalc include a Ford Ka with a forecast used value of £15,000 after three years, two BMW 5-series from the same year but straddling a model change, both listed at the old model's future residual value, and a range of cars with VAT added twice.
CAPcalc manager John Watts said: 'These are typical examples of the kind of seriously misleading information that can emerge from simple human error when building and maintaining fleet databases.
'Multiply such mistakes by the typical levels we are finding and fleet professionals and finance directors clearly run the risk of relying on inaccurate information on which they may be basing important business decisions.'
CAPcalc uses CAP data to produce current revaluation, historical analysis and future residual performance forecasts which can indicate error rates on fleet databases.
Watts added: 'Because CAPcalc uses the CAP code system it is able to highlight all vehicle identification errors, for example in a live database.
'This is invaluable for businesses that want to have the clearest possible picture of their fleet portfolio value today and in the future.
'Customers favour the system because it uses 100% CAP data, which already underpins many of their fleet value-related business decisions.'
CAP says fleets can benefit from a revaluation service as it provides an outline of current and future financial exposure.
It will allow fleets to identify the best residual value performers and can see the highest risk vehicles on the fleet.