"The performance has fluctuated in the first four races", said the Austrian.
The silver arrows aim to continue their unchallenged domination of the 2019 F1 season, but team boss Toto Wolff was sceptical heading into the Spanish Grand Prix. We knew that we had the pace to score those points, but bad luck and events out of my control had prevented it until then.
Asked about his comments, Vettel told a news conference: "The vehicle, I've tried".
The only big difference this weekend compared with others is the number of upgrades on the cars.
Hamilton was unhappy with the performance of his car's tires in the first session when he was fourth fastest and set his best lap on softs. So, could Friday's woes be solved with a better understanding of the data and some setup tweaks overnight?
The current layout is a mix of fast and slow corners and Turn 3 is especially demanding, requiring a well balanced auto. "But this is a thing that can be fixed and also things that are not un-normal when you are putting new parts on the vehicle".
But drill a bit deeper into where Ferrari is losing time and it's a familiar picture that emerges.More news: US Secretary of State Pompeo makes unannounced trip to Iraq
The Finnish driver, who now leads the championship by one point from his English teammate, looked comfortable on a sunny day at the Circuit de Catalunya in Barcelona.
Binotto said Ferrari's stance on that could change as well. "Obviously slow corners can be nasty because if you don't have a lot of grip you lose quite a lot of time". Bottas was quickest in the first two practice sessions but Hamilton had the edge on Saturday morning, nearly half a second up on Leclerc. Bottas was much happier - something that was visible from the car's behaviour on track - and believes Mercedes has made a useful step from the last race two weeks ago.
Hamilton will likely be confident of doing his part due to his strong recent record at the Spanish Grand Prix and, with the help of Opta, we bring you the key stats ahead of this weekend's race. Everything based on winter testing, this seemed to be a track that really suits them and since the practice, we saw yesterday that we were in good form. "I hope this might be the moment to put that right". "It's always such a special occasion and I can't wait to see all the fans in my grandstand, I'm looking forward to seeing it in full papaya!". I think Melbourne, we were stronger.
"We have to remain positive".
On the long runs, the Mercedes advantage appeared to increase.
The Briton, victor for the past two seasons in Barcelona and three times in all, said Bottas had simply been quicker on the day.
After new upgrades the Haas F1 team will start with both Romain Grosjean and Kevin Magnussen on the fourth row for the Spanish Grand Prix, but the real test of that upgrades package will come on. The other three drivers (Nico Hulkenberg, Lando Norris and Carlos Sainz) will receive the update on Saturday.