Carlos Sainz took to his Renault RS17 as a fish to water in Austin for his maiden race with the French team, and was the first to be surprised by his pace.
Sainz outran team mate Nico Hulkenberg in both free practice sessions on Friday, and was hot on the heels of the German in FP3, concluding his morning P8, just 0.042s adrift.
"If you would have told me yesterday I have would been on the pace today immediately I would have signed the paper," Sainz said after his first run in the RS17 yesterday.
"So I have to be happy with that. It was interesting. To have the chance to drive two different cars in one year gives you a lot of information, a lot of things to feel, to test.
"It has been a very interesting day for me, FP1 in particular, feeling the car in wet conditions and onto dry conditions."
Anyone believing his task was perhaps facilitated by his RS17 using the same engine as his former Toro Rosso would be making the wrong assumption.
"What you really want to adapt to is the brakes, to the power steering, to the balance of the car, all these kinds of things I've been adapting to little by little through the day," he explained.
"I'm still not 100 percent there yet, still need to leave some space in the back of my mind to feel the different stuff going on in the car, but hopefully as I do more laps it will become more natural, more automatic.
"I will need to keep adapting and keep adapting, and I'm sure at the end of the weekend I will still not be 100 percent.
"So we need to go little by little like we are doing now, covering all the basics, and hopefully we can be nearly there for qualifying, and nearly there for the race."
Sainz also said it would ill-advised to make any comparisons between his former and current mounts.
"I think it's not fair to start comparing publicly car behaviours, or anything like that. I'm going to keep that in my pocket and use it for my benefit."
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