12K seems way too low. For a company in business over a 100 years that would result in an average of only 120 per year.
Not sure I know of a year when that few cars would have been made, and several of the older marque books report on some early three wheeler years where over a thousand cars per year were produced. The MMC has made some 1500 M3Ws since 2011. That is in only 4 years of production.
So I think we best approach it using other sources than the DVLA.
Cheers,