It’s amazing what you can find on the internet.
There’s been plenty of conversation about the Holden Commodore switching to a 2.0-litre turbocharged four-cylinder for the latest ZB generation, however, it turns out the concept of a turbo four-pot Commodore has been around for 25 years.
An article written by retired 42-year Holden veteran, Neil Pogson, for the Holden Retirees’ Club archive details how close Holden came to offering the VP Commodore with a 2.3-litre turbocharged four-cylinder sourced from Saab.

South-East Asian nations placed punitive taxes on vehicles with large engines, forcing Holden to replace the local 3.8-litre Buick V6 with either GM’s Family II 2.0-litre four-cylinder of an Opel-sourced 2.6-litre straight-six, neither of which was deemed ideally suitable.
Styling changes were also required, which Holden managed by fitting the Caprice front-end and boot to the standard Calais (these changes made it to production), but of more importance was a competitive engine. GM owned 50 per cent of Saab so the Swedish firm was contacted and agreed to adapt its transverse turbocharged four for the Commodore’s north-south installation.

Even allowing for the torque limitations of the Hydramatic auto gearbox the Saab four-pot was capable of 150kW/300Nm, well in excess of the 127kW/293Nm produced by the Buick V6 at the time. Unfortunately, GM internal politics killed the project and the mules were crushed, but to find out more you’ll have to read Pogson’s story!