1970 Vauxhall Viva HC

Little changed underneath the Viva HC when it appeared in 1970, for the engines and platform were carried over from the HB. However, the bodies – available as saloons, estates and coupés – were restyled for the new decade, adopting a square-cut style (on the saloons) more reminiscent of the HA than the HB. Within a few years, a range of new engines was introduced; 1256cc, 1759cc and 2279cc. To make the higher-powered cars stand out, they were badged as Magnums from 1973, the coupés were also known by this name for just over a year as well.

info from Octane