Start with what the Packard Model G is: a car with gasoline engine, from Packard. What it meant takes a little longer.
How it came about
Packard Model G is a two cylinder car built in 1902 by the former American automobile manufacturer Ohio Automobile Company that changed its name to Packard Motor Car Company in October 1902. At that time the company was located in Warren, Ohio; owners were brothers James Ward Packard and William Doud Packard and investor George Lewis Weiss.
Model G was a development of the former single-cylinder cars the company had built since 1899 of which the last, Model F, was offered alongside the Model G. Introduction was in late summer 1902. Only four cars were built.
The hardware
The engine is gasoline engine. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Family and rivals
Its Packard stablemates include the Packard 160 and the Packard 180.