Gearbox problems prevented Sauber from scoring a point at the Hungarian Grand Prix.
Esteban Gutierrez retired after 28 laps while Nico Hulkenberg also suffered gear selection issues which contributed to a drive through penalty.
"It was a pity what happened," said Gutierrez.
"We were on a good strategy and everything was running as planned. Unfortunately, we had to retire due to a gearbox problem. This is not really the best way to finish a race, but we did everything we could during the weekend. We had an engine problem yesterday and now the gearbox during the race, so this is something we have to look at to avoid it happening again. It is frustrating, but we need to stay positive and look forward to the next events, because we can see our performance has improved."
Hulkenberg believes he missed out on a top 10 finish after gear selection woes.
"The race was all right up until the second pit stop. I had trouble shifting from first to second gear," he said.
"There is only a certain window where you are able to do that, otherwise it won’t shift. That didn’t work, it got hectic and somehow I must have released the button too early. Without the drive through penalty we could have clinched one point. Overall, our pace was ok, but not good enough to get into the points easily."