I like how you Americans call the Corsa a 'super-mini'. It's not a big car but its definitely not supermini. It seats four people without problems. Hehe.
Supermini is also referred to as the b-segment in europe which the corsa is part of, so yes it classifies as a supermini. Its only 159 inches long. That is very small.
http://en.wikipedia.org/wiki/Opel_Corsa