Max Verstappen spent the whole day in the car, which is substantially different from its title-winning predecessor, setting a best lap that was 1.1 seconds clear of the McLaren of Lando Norris.
Marko says that the team’s new concept is working and that the car responded well to changes.
"Very, very, very impressive,” said the Austrian. “We ran 142 laps, without any problems, more or less. And the concept is working. So that was the first main thing. The car is reacting, and we are developing. Yeah, it looks good."
Asked about Verstappen’s take on the car, he said: "Positive. Whatever changes we did and whatever we tried, the car was reacting, and more or less it was fine-tuning, what happened now. We all were smiling a lot.”
Marko admitted that the team had taken a chance by making such a radical change between seasons.
"I mean, it's always a risk,” he said. “And if you look at Mercedes, they had some problems, and our car was working from the very first lap. So we are very proud and glad.
“Also, the reliability is unbelievable. And [from] what I saw tyre-performance-wise, again, Ferrari has more problems than us.
“Also, the McLaren seems to be a little bit more nervous. Mercedes, I don't know what they did. For sure they are faster than what they have shown. But we can be confident."
Asked if he had expected rivals to make more of a step with their cars, Marko couldn’t resist a dig. "I think they didn't expect what we would do,” he said, adding: “How should I say? The cars all look like [ours from] last year."
Regarding the prospect of others copying the RB20, he said: "It takes a while to do such a concept."
Verstappen himself agreed that the new car was reacting well to changes.
“We covered a lot of laps and tried quite a few things with the car, which was important,” said the world champion. “So happy overall with how it went.
"After the winter break, the first few laps always surprise you a little, but then you get back into the swing of things pretty quickly.
“Overall, the car was responding well, and considering this was only testing, we had a nice day. Looking to tomorrow, we are speaking to our engineers about what the plans will be, but I am looking forward to getting into the car in the afternoon.”
