Chevrolet's entry was the Corvair, which I wrote about here, a radical (for the USA) design featuring a rear-mounted air cooled motor. Shortly after it was introduced, Chevrolet management realized that Corvair sales would be eclipsed by the conventional Ford Falcon. So, as this Wikipedia entry reports, a crash program was started to produce a car that could compete with the Falcon. The entry quotes stylist Clare MacKichan regarding how rapidly the design had to be productionized ... a matter of around 18 months instead of the usual three or four years.
The first-generation Chevy II (1962-1965 model years) was almost exactly the same size as the Corvair and Falcon. Respective wheelbases were 110, 108 and 109.5 inches (2,794, 2,743 and 2,781 mm) and overall lengths were 183, 180 and 181 inches (4,648, 4,572 and 4,593 mm).
Back around 1960, entry level American cars were seldom very exciting from a design standpoint. The Chevy II fit that pattern well, being bland and having no distinct character -- though the same could easily be said about the Falcon as well.