Sauber will bring major upgrades to next weekend's Spanish Grand Prix as they bid to turn around their fortunes in 2014.
Sauber has yet to score a point so far this season, with Adrian Sutil's 11th place in Australia their best result.
Reliability has also been an issue, with Sutil finishing just once and team-mate Esteban Gutierrez twice. Sauber's C33 will be 'significantly improved', according to the Swiss team.
Sauber will bring a car with an extensive weight reduction - an aspect which has particularly hampered Sutil in 2014.
A 'major aerodynamic update' is also planned.
"We will be travelling to Barcelona with some car updates, which I hope will help us to improve our performance," said Sutil.
"Obviously, I expect more than in the last races. After three retirements in a row, we need to finish this race. I am looking forward, and I think that our performance will be stronger than in the previous races."