Marcus Ericsson says he can leave Sauber feeling “proud” of the role he played in helping the team’s Formula 1 recovery bid.

The Alfa Romeo-backed Sauber team enjoyed vast improvement in 2018 as it moved up from the bottom of the constructors’ championship to eighth place thanks to its 48-point haul scored by drivers Ericsson and Ferrari-bound Charles Leclerc.

Ericsson joined Sauber from Caterham in 2015 but following a promising start, a lack of development amid off-track financial issues resulted in the Swiss squad slipping towards the bottom of F1’s pecking order until it received fresh investment and closer ties to Ferrari last year.

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“When I came here we had a great start to 2015 with some strong races, strong results, quite a lot of points,” Ericsson said.

“But then sort of halfway through that season it became like a survival mode type of racing for two and a half years almost.

“It was very tough times for the team, we were struggling a lot being less and less competitive and that was making it very difficult for you as a driver.

“We were really at rock bottom,” he added. “But then we were able to turn that around and then to be part of that transformation we’ve had that last 12 months has been very fun.

“I’m proud of being part of that, this last season has been really great for the team and me myself as well.”

Despite enjoying his strongest F1 season to date, Ericsson lost his seat for 2019 after Sauber opted for a new line-up consisting of Kimi Raikkonen and Antonio Giovinazzi.

Asked how it feels not to be involved in the next stage of Sauber’s revival, Ericsson replied: “That’s the disappointing part - not being able to continue it.

“Because I’ve been here throughout all the bad times and then now through the good times this year and I feel very much part of the journey with the team, with everything that’s been happening.

“That’s why it’s sad not to continue with that because now it really feels like we’re starting to hit out stride as a team and we really starting to fight higher up the field.

“It would have been nice to continue that for next year but that’s the way it is.

“I’m still proud of what I’ve done and I feel I’ve been very much part of what the team has become today.”

Ericsson will switch to IndyCar for 2019, where he will drive for Schmidt Peterson Motorsports.