Yuki Tsunoda described the Red Bull car as "very different" to what he is used to, after an encouraging maiden test for the squad on Tuesday at Yas Marina Circuit.
The Japanese was finally given a proper test in one of Red Bull's cars during the post-season Abu Dhabi tyre test.
While lap times were largely irrelevant because of the different run programmes that everyone was doing, Tsunoda said that he had never been happier than when lapping in the RB20 which finished third in the 2024 constructors' standings.
"You can physically feel why the RB20 has been fighting for a championship this year, it feels like a very different car to drive," he said.
"We have had a very proactive day today so I am really happy with that. There is still a lot of learning that I have to do, but the team have done a great job of preparing such a great run today. It's been such an enjoyable atmosphere in the garage."
Tsunoda said before the run that he expected himself to be well suited to the car's characteristics after trying it out in the simulator, and that proved to be the case.
"I feel like the car suits my driving style and I haven't struggled much at all to adapt," he added.
"Even on the long runs I have been able to run consistently today and was able to feel the limitations of the car which, if you don't have confidence in the car, you are unable to test.
"I am happy more than ever at the moment, and making sure that the team have the information that they require from each run was the most important thing to get out of today."
Tsunoda is hoping that some positive feedback from the test can convince Red Bull's bosses to promote him to the main squad next year if it goes ahead and chooses to drop Sergio Perez.
The outfit has previously been reluctant to do so because of concerns about Tsunoda's temperament and level of technical feedback.
However, it was interesting that head of performance Ben Waterhouse said afterwards that he had been impressed with how the 24-year-old operated.
"We had Yuki in our car for the first time and Isack [Hadjar] driving RB20 again following his recent outing in FP1 at the race weekend," he explained.
"We successfully completed the priority test items on both cars with both drivers performing to a very high level and delivering exactly what we anticipated from them.
"Yuki provided excellent feedback on the various tests performed on the 2025 Pirelli tyres offering valuable insight on the tyre changes Pirelli will introduce for next year, while Isack did a great job and successfully completed all the procedural aero tests in the morning before performing both long and short runs evaluating a range of test items in the afternoon."
