The team enjoyed one of the most successful seasons in its history in 2012, as it claimed four podium finishes and finished sixth in the constructors' championship.
Team boss Monisha Kaltenborn said that given last year's results, Sauber wanted to build on the previous car's strong points rather than starting afresh.
"I'm very excited, but also a little tense," she said. "The aim is very clear and simple: we want to continue to improve ourselves.
"The Sauber C32 is based on its predecessor, which was a very competitive car.
"It had a lot of strengths and some weaknesses, and our engineers have worked to build on those strengths and eliminate the weaknesses."
The car has an all-new, largely grey, livery and runs a smooth nose as well as notably small sidepods.
Sauber also has an all-new driver line-up for 2013, with ex-Force India man Nico Hulkenberg and promoted test driver Esteban Gutierrez replacing Sergio Perez and Kamui Kobayashi.