The best German private trackers where it is relatively easy to get an invited are probably TN and IM. They don’t get many releases as fast as the top tier trackers but an active requests board. And yeah Content on public trackers is basically nonexistent. For automation and little work Usenet indexers like scenenzbs are a good route as well
But the firemen would just call it by it’s abbreviation HLF of course
And obviously there is a norm for all Vehicle types in use. Here is a list of all of them https://de.wikipedia.org/wiki/Feuerwehrfahrzeuge_in_Deutschland#Feuerwehrfahrzeug-Typenliste_der_aktuell_genormten_Fahrzeuge