Start with what the HSV W427 is: a car with gasoline engine, from GM (General Motors). What it meant takes a little longer.
Under the skin
The engine is gasoline engine. On the scales it comes to 1874 kg. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
In context
Nearby in the GM (General Motors) catalogue sit the 1955 Chevrolet and the 1957 Chevrolet.