RTS made significant changes to the suspension of the car, greatly improving the handling finesse, while at the same time not compromising ride quality.

During the course of the HZ series, equipment levels were upgraded in 1978 effectively to match improvements in the opposition Ford Falcon range, but the life of the full W size Holden looked set to end following Holden's release of the VB Commodore in November 1978.

[3] The Holden HZ was offered in four sedan and three station wagon models, marketed as follows: It was also available in two ute, two panel van and one cab chassis model, marketed as follows: There were two special vehicle packages also available based upon commercial vehicles: The final HZ Sandman, featured a choice of V8 engines only, along with a four-headlight grille and under bumper front spoiler.

If a buyer selected every Sandman extra, the price would be more than 150% of the cost of the basic HZ model.

By the end of 1979, the Sandman had largely lost its place in the contemporary Australian youth culture – order figures were down and many of the vehicles were now being sold with the stripes and tailgate logos deleted.