Sauber left the Bahrain Grand Prix empty handed after a difficult race for both Nico Hulkenberg and Esteban Gutierrez.
Hulkenberg finished in twelfth place, with Gutierrez down in eighteenth.
"It was a difficult and frustrating weekend," said Hulkenberg.
"It was clear from the beginning that we were not fast enough and that it would be challenging. We are lacking speed and eat up the rear tyres too much so it simply wasn’t enough this weekend. We pitted a bit too late, because we expected to have more problems on low fuel, which in the end we didn’t have. That cost us at least one position. This weekend clearly showed we need to bring some new parts to Barcelona in order to improve our speed and fight for points."
Gutierrez damaged his wing on the opening lap and spent most of the race among the Caterham and Marussia drivers.
"I expected a difficult race and this is what I got. We need to find more speed," he said.
"On the first lap I had contact down into turn 10, which was really hard to avoid. Apart from that, things were quite ok, but, of course, finishing a race like this is definitely not enough and we need to improve. We have to analyse the strategy and hopefully we will bring some good updates to Barcelona."
Team principal Monisha Kaltenborn has urged Sauber to improve.
"We can’t be satisfied with this race," she said. "We knew this track would be difficult for our car, but this cannot be an excuse. It’s important that we gathered a lot of information over the last two races, which we will use as a basis for the development of the car. Nico drove a good race, so it is now our job to provide him with a quicker car."