George Russell believes the W13 is now "well over a second" quicker than it was at the start of the season, following his first Formula 1 win at Brazil.
The team has enjoyed a resurgence lately after introducing a new aero package at the US Grand Prix, which has enabled it to challenge for wins.
Given that they were the team that suffered the most from porpoising at the start of the season, Russell hails the team's progress in the last few races.
"Definitely well over a second [quicker than Bahrain], I would say," says Russell to media, including RacingNews365.com.
"I think in Bahrain I qualified ninth. At Imola, both Lewis and I were out in Q2.
"We were fighting with Alfa Romeo and Haas at the start of the season and well over a second behind Ferrari, who were looking the most dominant team at the time.
"I think it really goes to show the improvements we’ve made."
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Russell: Now we're focused on bringing performance
The Mercedes driver managed to finish in the top five for the first nine races, before having to retire at the British Grand Prix when he was caught up in the crash with Zhou Guanyu.
Despite a pole at the Hungarian Grand Prix, the team was once again plagued by proposing issues at the subsequent race in Belgium.
Russell believes the team lost a lot of time trying to solve the porpoising problems with the car, which hindered their ability to introduce performance upgrades.
"We lost so much time trying to solve the porpoising issues and that really hurt our development.
"I think that's why we're seeing such a jump in performance in these past eight races.
"It’s because we’re no longer focusing on the porpoising and we're now focused on bringing performance."