(Reuters) - Struggling Sauber hope to score their first points of the Formula One season in Spain next week after making the car significantly lighter.
The Swiss team's head of track engineering Giampaolo Dall'Ara said the cars had seen an "extensive weight reduction" since the last race in China.
Drivers Adrian Sutil and Esteban Gutierrez have both drawn a blank in the first four races.
Dall'Ara said a "significant" aerodynamic update included a modified front wing, new engine cover and side-pod fins and deflectors.
"Besides that, we will also have a software improvement which will enable us to use the potential of the power unit in a better way," he said in a team preview for the first European race of the season.
Sutil hoped to see a step forward: "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," said the German.
(Reporting by Alan Baldwin, editing by Ed Osmond)