As with all large government databases, there are errors in this dataset
(especially since quite a lot of the data for older vehicles is based on
paper records that were originally maintained by local authorities).
The most common error that crops up is vehicles that don't have
exactly the correct model variant recorded on their V5 registration
document. For example, a special edition
Peugeot 205 Gentry
might only have Peugeot 205
recorded on its V5. This can lead to some model variants appearing to
be rarer than they actually are.
The key to understanding whether or not the data is accurate for your
particular model is to check the model name on its V5 registration
document. If it's not what you expect it to be, then it's likely that
the DVLA statistics for that model aren't very accurate!
This happens more often with older vehicles, especially for those that
would have originally been registered in the 1970s and earlier.