I mostly know Leiterwagen or Löschfahrzeug or Einsatzwagen. Feuerwehrauto is what children say. Also “Wagen” makes sense because when there is an emergency you refer to the multitude of vehicles that move out and the group of people as a “Löschzug” an “extinguishing unit” but Zug also means train and a train has “wagons” -> Wagen

So we have this verb and the ending in third person plural is -ent but we just dont pronounce that so it pronounces the same way as third person singular…

Meanwhile there is many words that are just two words in english instead of a compound word.

Lets take a typical example for “business” compound-words:

IT-Sicherheitsdienstleister -> IT security service provider.