Toro Rosso conducted development work on both the car and the driver fronts, entrusting its STR12 for the day to rookie Sean Gelael.
The Indonesian F2 racer suffered an issue in the morning when his car grinded to a halt with a mior electrical problem.
He was back in action shortly afterwards and consistently worked his way through the team's program, and finished his session a very happy young man.
"Today is a day I will never forget – to finally drive a Formula 1 car is something every driver dreams of, and to do it with Scuderia Toro Rosso makes it even more special," Gemael enthused.
"What an amazing feeling! This year’s car is a beast, it’s so quick! I settled in nicely throughout the day and we definitely made progress.
"I was able to complete plenty of laps and get used to the car quickly. The power and overall grip is amazing and, compared to the Formula 2 car I drive, the grip under braking and the kerb riding are two of the biggest differences I felt.
"Honestly, it’s really fun to drive and I’d like to thank everyone who made this possible! I now can’t wait to drive the STR12 again in a few months’ time at the test in Hungary."
Toro Rosso head of vehicle performance Jody Eggington praised the 20-year-old's contribution and performance.
"Sean acclimatised himself very well, covering a number of test items across a range of tyre compounds, gathering some very useful data for the team.
"He drove consistently, making no mistakes and he therefore should be very happy.
"We will head into tonight with a lot of data to analyse and a further packed run program for tomorrow – Daniil will be driving in the morning and Carlos in the afternoon."
GALLERY: All the action from the Day 1 in-season testing at Bahrain
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