I guess Australia dropped the Vauxhall early on because they competed with Holden, and then the Zephyr when the Falcon came along. When I was in Melbourne in 1980 I saw MkII Zephyrs, but no MkIII's, let alone MkIV's.
Love the Supersnipe's, came close to getting one oof those old ones a couple of times...they were huge. Knew a guy in Taranaki who put the 6 cyl Perkins engine out of his Fergy into one. We went for a drive in it, a lot of laughs, but could only do 50mph.
The Zephyr was such an icon in NZ, they made a movie called Zephyr MkII.