Esteban Ocon believes it was "crucial" to drive Renault's 2019 Formula 1 car at Abu Dhabi, as it will "help massively" in light of next year's reduced testing schedule.
Ocon, who replaces Nico Hulkenberg in Renault's 2020 F1 line-up, was released by Mercedes so he could test for his new team during this week's two-day post-season tyre test.
The former Manor and Force India driver said after his first day in the car on Tuesday that he believes this will be integral to his preparations for next year, as F1 has cut its pre-season testing allocation from eight days to six.
"It's crucial and definitely it's going to help me massively," said Ocon.
"Because you arrive to testing in February with an advantage, because you have your position [in the car] fixed, you have things that you verified on track, which it's great to have the chance for that.
"I didn't get much driving time this year, and to have even fewer days in February, it's a big problem.
"So to have these two days here it's basically a counter for the days we are lacking in February."
Ocon, who served as Renault's F1 reserve in 2016 before his stints at Manor then Force India, ended the opening day of the test in eighth place, 2.838 seconds off the pace.
Tyre supplier Pirelli revealed that Ocon's mileage was limited by a seat problem, and he confirmed the seating position was a marked difference compared to Mercedes' - as its race drivers are shorter than Renault's 2019 line-up.
That aside, Ocon enjoyed a "pretty smooth" day.
"It's a fantastic feeling, to be back," he said.
"I was so excited for today, I've been waiting for that day for months and finally it happened.
"Good first impression, the team gave me a very warm welcome, which is always very satisfying. Seeing some old faces, some new faces as well, which is great.
"And we properly started to work on all the little details, and towards the afternoon I started to get closer and closer to the limit."
Asked what he made of the RS19, he said: "It felt good. Obviously there's always a lot that you can improve, but the engine is also something new for me since a couple of years - good power.
"Then, of course, the balance, you need to always work on it. I think we have a solid base that we can continue [from on Wednesday]."