Inevitably, the trendsetting two-door Monaro had such a strong influence on the rest of the Holden range that sedans took on a similarly sleek look. The process began with the HT sedan's 'faster' roofline and became more apparent with the arrival of the fluid HQ. So it was in the course of this model's long-selling life that Holden took the opportunity to test the waters with a four door Monaro.

In 1972, Holden had offered a limited edition sedan based on the entry level Belmont. The first SS, it was transformed by sports wheels, GTS grille, side vents, blackouts, black boot panel and unusual bonnet stripes from the headlights to the front scuttle panel. Backed up by a 253 V8 (4.2), Aussie four speed manual, bucket seats, sports steering wheel and GTS instruments and finished in 'Infra Red', 'Ultra Violet' or 'Lettuce Alone' green, it became a huge hit.

The first four door GTS Monaro arrived in 1973. It featured new contoured front seats, trimmed in a sophisticated herringbone pattern. Black SS bonnet and boot patches were replaced by louder GTS rally panels on the bonnet and boot lid. They did the trick; there was no mistaking the GTS Monaro four door for any other of the 250,000 HQ Holdens already on the road.

By this stage, the Monaro GTS 350 - coupe or four door - became a rarer beast as more Australian drivers opted for the home-grown 308 V8. The final four door HQ Monaro GTS 350 examples still made a fabulous farewell to the Chevrolet small block V8 with Salisbury rear axle, Muncie four speed and 70 series radials.