Felipe Nasr says his Sauber team needs to take some "bigger steps" in order to fight for the points regularly next season.
The Swiss squad has bounced back from a disastrous 2014 season in which it scored no points to be eighth in the championship ahead of McLaren and Manor with 34 points in its 2015 tally thus far.
And Nasr says the Swiss squad knows where it needs to improve and is already hard at work to be able to fight in the top 10 more regularly.
When asked if he was already working on the development of next year's car, he said: "A long time ago. We have been already focusing on the 2016 car.
"We've been always discussing that with the team and it's clear we have to do some bigger steps."
He added: "The main area is we need more downforce. That's the initial point. We know the car is weak, we know where the car is strong.
"I think Marcus understands as well what are the priorities at the moment, so I think we are both giving the same input."
Pleased with season
The Brazilian said he was happy with how he has performed during his first season in Formula 1, having finished in the points five times, including a fifth-place finish in his first grand prix in Australia.
"Overall it's been a very positive season. I've had some great moments," he said. "We've had good and bad results, that's how things go, but overall it has been very positive.
"When I had the opportunity to score points and to show my potential and to show why I'm here, I think I took most of them.
"On the other hand we had some issues in the middle of the season, but that's normal. It happens with everyone, but the good side of things is to have a positive overall balance in the end.
"I scored good points, I did fight with some stronger cars, and I think that's what people want to see."
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