 They launched their first four wheeled truck within the 1500 KG to 11000 KG gross weight categories.Also available was an 18-28-seater bus/coach model, both of which were part of the model range in the 1950s and 1960s.One of the most interesting applications of Avia trucks was the Klöckner Humboldt Deutz Spanish subsidiary designed Avia-Deutz firefighting engine.