The shorter, slower nature of the Hungaroring is not expected to suit the SF90, which has been mighty in straight lines all year but has shown crucial weakness in the corners.
However, Vettel managed to almost exactly match the time of Max Verstappen in Friday's first practice session, just a tenth of a second down on Lewis Hamilton atop the timesheets.
A drizzly FP2 offered a chance for running in changing conditions, but Vettel is confident whatever the weather.
"I think in both conditions we should be thereabouts; how close, we will see," Vettel said. "I think Mercedes look very strong out of the box straight away."
The German's view is in slight contrast to his team-mate, with Leclerc seeking assistance from the skies on qualifying day.
He said: "I think in the wet, I was in better shape. Overall we are struggling a little bit with the downforce level that we have.
"It's a track where we need a lot of downforce, we knew it would be a difficult track for us, so we need to work and try to improve for tomorrow.
"It will be all about trying to anticipate what will happen on the Sunday," he added. "I think everything will be quite different on Sunday, a lot warmer than it was today, no rain, so yeah, we will see Sunday.
"Obviously it was all about the laps before in the conditions which were changing quite a lot. We'll see tomorrow. Hopefully it will rain."
GPFans is a multi-platform, multi-language brand dedicated to Formula One coverage. We bring you all the ins and outs of the sport, 24/7, everything from up-to-the-minute news and features to the latest viral stories and clips.
We believe that a new generation of exciting, outspoken drivers will make F1 more popular than ever before, and we want to give our users access to as much of their heroes as possible, on and off the track. From Lewis Hamilton to Max Verstappen, Daniel Ricciardo to Sebastian Vettel, we provide in-depth analysis of every every Grand Prix in the season, from Australia to Abu Dhabi.
With Formula One under the new ownership of Liberty Media, how the sport is being covered is evolving, and GPFans will look to be at the heart of this progression into new media, as one of the fastest-growing sites covering the king of motorsports.