Reason for the uncommon German license plates in "Hanna"

Question

Being German myself, I've noticed that the German license plates in Hanna have quite a strange format, it's something like

B-123-ABC

whereas the common format is

B-AB 1234

Where the first part (up to three letters) stands for the city or district that issued the license, and the second (two letters) and third (one to four digits) identifies the actual license.

While there are some special formats for license plates, the one used in Hanna did never occur to me.

Are there any in- or out-of-universe explanations for the format? I thought about legal issues when using real license plates, but there are other productions using real license plates, too, therefor this does not seem to be a general issue. I did not care about it all the time, but whenever I did, all cars seemed to have those license plates, hence I tend to rule out the format being reserved for "officials", too (Hellers team had one of those license plates, too, after all).

(Googling the issue yielded no results, too, but it may have been the wrong search terms)

Answer 1

This is specifically for German legal reasons detailed here at the wiki

There is not an English language version of the article, and my translating skills aren't the best,

However the main reason(s) is that specific letters are allowed up until specific years and specific combinations again up until specific years of fictive plates and in fact even real plates are allowed, barring permission.

I dont know the specific production company of Hanna (is it a German production?) But if they’re filming in Germany regardless these are the rules they’d have to abide by. And likely they opted for fake ones, instead of getting permission from every owner of every car for every scene.

Answer 2

Season 1 of „Hanna“ has been filmed in Slovakia and Hungaria (see https://en.wikipedia.org/wiki/Hanna_(TV_series)#Filming). There are a lot of scenes pretending to be in Berlin, but they are not. The license plates look like older ones from Bucharest (Romania). Quite conveniently starting with the same letter as Berlin.