The HB Viva, announced in September 1966 and sold by Vauxhall until 1970, was a larger car than the preceding HA, featuring coke bottle styling, and was modelled after American General Motors (GM) models such as the Chevrolet Impala/Caprice of the period, and in no way was related to the Opel Kadett - as had been the case with the HA. It featured the same basic engine as the HA, but enlarged to 1,159 cc, but with the added weight of the larger body the final drive gearing was reduced from 3.9 to 1 to 4.1 to keep the nippy performance (except the SL90 which retained the 3.9 diff having the power to cope with the higher ratio).

Apart from the standard and 90 stages of tune, there was also, for a brief time, a Brabham SL/90 HB that was purported to have been developed with the aid of world racing champion Jack Brabham. The Brabham and the Viva GT are the two most sought after models made. The Brabham model differed from the standard Viva SL/90 in having a different cam-shaft, uprated suspension with anti-roll bars, different exhaust manifolds, and a unique twin-carb manifold, as well as differing interior trim. The Viva GT had substantially different engine and running gear and interior from the standard Viva HB models. It was distinguished by having a black bonnet with twin louvres and being all-over white. Later GTs came in a choice of colours. Two larger overhead camshaft engines from the Vauxhall Victor were also offered – a twin carb 1975 cc in the Viva GT from Feb 1968 and a 1599 cc making up the Viva 1600 from May 1968.