Max Verstappen and Pierre Gasly put the first serious miles on the new RB15 as Formula 1 pre-season testing began on Monday.
The Red Bull Racing duo took it in turns to get to grips with their 2019 machine at the Circuit de Catalunya in Barcelona, Spain, after the winter break.
Verstappen completed more than 125 laps on the opening day of testing as he got to grips with the new Honda engines, and then took over duties again on Wednesday.
Speaking after his stint on Monday, Verstappen said: “To do 128 laps on the first day of testing is a really good day, so I’m very happy with that. We collected a lot of data, which is really important, and we’ll analyse everything tonight to see what we can improve on tomorrow when Pierre is in the car.
“I’ll also go into detail tonight and tomorrow to see where I can improve for my second day. So far, so good and I’m happy that we were able to do so many laps. I’m looking forward to the rest of the week.”
Gasly raced with Honda power units at Toro Rosso last season before making the switch to Tilbrook.
“The day was positive and I was really happy to be back behind the wheel after the winter break” said Gasly after his stint on Tuesday.
“The first feeling is good. It was important for me to get comfortable in the car and we managed to do more than 90 laps.
“This afternoon, I was pushing and out of Turn 10 I went on the power, upshifted to fifth and lost the rear of the car. It was quite annoying to lose the last hour of testing. Apart from that, we tested a lot of things and got a lot of good information, there is a good potential.
“Of course we still have a lot of work to do over the next six days of testing but for me, aside from the last bit, the first day was great.”
Verstappen put another 109 laps into the car on Wednesday, and with Daniil Kvyat's Honda-powered Toro Rosso setting the quickest time of the day, it showed the potential in the new engines.
Verstappen said: “I think today was really positive. Whenever you do more than 100 laps at a test, that’s a good day. I’m happy with the way we’re working together with Honda so far, it’s very focused and everybody knows their job. What’s most important is that we have completed a lot of laps and investigated many set-up changes. With different regulations, you have to understand what direction to go in and that’s exactly what we’re doing.
"So far, it’s difficult to judge where we are compared to the other teams – we’ll find that out in Melbourne – but at the moment the car feels good.”