You may be able to find out here, in the search box, try Subaru Impreza, and then whatever the model says on your V5

https://www.howmanyleft.co.uk/

Only 94 WRX STi Spec D's left on the road now, plus 83 currently SORN'd as of Q1 2022. They made 300 of these models.
The how many left site does have turbo lag though, and seems to often be about 3-6 months behind the current picture, but probably fairly accurate in real terms, and certainly a good rough idea.

 

only applies to the UK and only if they were ever actually registered correctly with DVLA anyhows as they were strictly Japanese home market cars..........

the numbered plaque relates to how many made the Month.....

 

I thought thy just had a short production run? but what do i know! lol