Nico Hulkenberg says a "whole bundle of factors" beyond performance were behind the Renault Formula 1 team's decision to replace him with Esteban Ocon for 2020.
Hulkenberg's future at the team had been in doubt since June, when Renault admitted it was considering other options.
Ahead of the Belgian Grand Prix, Renault confirmed it had completed a deal with Mercedes to take Ocon on as Daniel Ricciardo's team-mate on a two-year deal.
Posting on his official Twitter account, Hulkenberg expressed his disappointment that his time at Renault was coming to an end, but he suggested that speed was not the only reason.
"It's a pity that the journey with Renault will end after the season, especially as we haven't been able to reach our goals yet," said the German.
"We had hoped to take another step forward this season, but unfortunately we haven't managed that so far.
"It is well known that the choice of drivers is not only about performance, it is a whole bundle of factors. But that's the way it is."
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Renault's decision leaves Hulkenberg chasing a seat elsewhere for 2020.
Haas team boss Gunther Steiner admitted on Thursday that Hulkenberg was on his team's shortlist - alongside Ocon and current driver Romain Grosjean - to partner Kevin Magnussen next year.
"Surely we would all have liked to see it differently but nevertheless, I'll keep my focus and try to reach the maximum success for our team in the remaining races!" added Hulkenberg.
"With regard to 2020, I am confident to find a good solution, but there is nothing to announce at the moment."