In the late 1960s and early 1970s, Gardner had two second-place finishes in the Australian Grand Prix – in 1966 at Lakeside behind Graham Hill and 1972 at Sandown behind Graham McRae.
A finais dos anos 60 e principios dos 70, Gardner terminou dúas veces no segundo lugar no Gran Premio de Australia, en 1966 en Lakeside detrás de Graham Hill e en 1972 en Sandown detrás de Graham McRae.