In September 1967 the sporty Commodore GS offering 130 PS (96 kW) from a dual-carburettor 2.5-litre six was introduced.

From September 1969, the base 2.5 L-engine was pumped up to 120 PS (88 kW); at the same time, both remaining engines received hydraulic lifters for smoother running, a new exhaust system and six camshaft bearings.

The handbrake lever was moved from its position under the dash to a location between the front seats and the fuel tank was enlarged from 55 to 70 litres.

It had a 2.5 L engine equipped with Bosch D-jetronic fuel injection system developing 150 PS (110 kW), which gave the car a top speed of 197 km/h (122 mph).

in 1970 the GS/E model was introduced which as its badge implies did not utilise carburetors, the "E" meaning Einspritzung or fuel injection in English.

Bosch D-Jetronic was a very early version of multi-point EFI, the “D” stood for “drucksensorgesteuert” (pressure sensor regulated).

Unlike later Bosch fuel injection system, the injection was direct to the cylinder instead of via the Plenum inlets, which meant the a specific cylinder head was manufactured specifically for the engine, making this model unique and expensive to produce and purchase.

Different from older mechanical injection systems, it incorporated taking input from the pressure inside the intake manifold.

Bosch sold the patent to Japanese companies that continue to produce injection systems based on D-Jetronic.

For comparison, the base model Porsche 911T in 1970 had 25 PS (18 kW; 25 hp) less, but was more expensive[citation needed].

The Royale sold well initially, but the car had not been re-engineered for Iranian conditions and the low ground clearance coupled with carburettor troubles led to its reputation quickly being tarnished.

The car was withdrawn by early 1977, replaced by the locally-built versions of the Buick Skylark, Chevrolet Nova, and Cadillac Seville (American origins).

The Commodore C was first shown in late 1977, at the same time as the Rekord E. It only entered series production in October the following year, however.

The South African version of this car, the Chevrolet Commodore,[8] was actually ahead of the European original model to enter production, in September 1978.

It was never offered by Vauxhall in the UK as a Viceroy, although a one-off estate car was built in 1981 for Queen Elizabeth II, for her to carry her Corgi dogs.

[14] Sold as a standard or a GL (with the 4.1 only available as a sedan with automatic transmission), the South African version replaced the earlier Chevrolet 3800 and 4100, also based on the Commodore.