Valtteri Bottas says he and Mercedes can still make substantial strides at Sochi after revealing the W11 was “too nervous” on low fuel runs at certain stages.
Bottas finished fastest during both 90-minute practice sessions for the Russian Grand Prix on Friday and was one second quicker than the best non-Mercedes driver.
However Bottas, and team-mate Lewis Hamilton, both made mistakes on their low-fuel push laps in second practice.
Bottas went wide through the final corner on his two push laps, losing time, and Hamilton locked up heavily into Turn 13, abandoning an effort that was half a second up on his previous best.
“Especially on the low fuel runs I always had some sort of problem with the rear end, so there’s something to look at there,” said Bottas, who claimed his maiden victory at the venue in 2017.
“It was more like rally-style driving than F1-style driving and I’m not sure that’s the fastest way around.
“There’s still a lot of time left on the table and, also, set-up wise, Sector One and Sector Two feel pretty good.
“But in Sector Three the car is still a bit too nervous and if we can get it right I’m sure there’s lap time there too.”
Bottas added that the “first session was pretty interrupted with red flags and everything but when we got running I had a big lock-up also, so I destroyed one tyre set.
“In the second session we actually got a lot of running but I didn’t manage to get all my sectors right in the same lap, so there’s definitively more to come.
“Actually, we had quite tricky conditions today, and that’s we saw a lot of people making mistakes.”