Silverstone double race winner Deagen Fairclough carried his form over to Donington Park, as he set the quickest time in all three sessions in the East Midlands on Thursday.
The British driver's best time came in the second test, with a 1m20.966s putting him 0.118s clear of Elite's Flynn Jackes, who was second quickest in both the afternoon sessions.
Xcel's Lucas Fluxa was third quickest, 0.090s ahead of Hillspeed's Dante Vinci, with VRD Racing's championship leader Nikita Bedrin fifth, and ensuring that five different teams were represented in the top-five.
The top-five all set their best times in the second session, with Elite's Kyuho Lee jumping up to sixth overall thanks to the lap in the final test.
The next 11 drivers recorded their best laps in session two, with Maxim Rehm the lead Rodin runner in seventh, and the final driver within half a second of the lead pace.
Xcel's Rowan Campbell-Pilling started his 'home' event in eighth, five thousandths of a second ahead of Hitech's Jacob Micallef in ninth, with the second Rodin car of Abbi Pulling completing the top-10, which was covered by 0.575s.
The top-15 drivers were all within a second of Fairclough's outright pace. A total of 21 drivers took part in Thursday testing, five of whom represented VRD, who handed testing opportunities to Ryan Giannetta, who races with the team in the USA, while Nadeem Rustombi returned to testing action also.
Three more sessions will take place on Friday, before qualifying and the first race of the weekend on Saturday.
GB3 Championship, partnered by the BRDC, Donington Park, Thursday combined test result:
1. Deagen Fairclough, Hitech, 1m20.966s
2. Flynn Jackes, Elite Motorsport, +0.118s
3. Lucas Fluxa, Xcel Motorsport, +0.299s
4. Dante Vinci, Hillspeed, +0.389s
5. Nikita Bedrin, VRD Racing, +0.397s
6. Kyuho Lee, Elite Motorsport, +0.422s
7. Maxim Rehm, Rodin Motorsport, +0.482s
8. Rowan Campbell-Pilling, Xcel Motorsport, +0.565s
9. Jacob Micallef, Hitech, +0.570s
10. Abbi Pulling, Rodin Motorsport, +0.575s
11. Ryan Giannetta, VRD Racing, +0.601s*
12. Martin Molnar, Rodin Motorsport, +0.677s
13. Peter Bouzinelos, Hillspeed, +0.867s
14. Jack Taylor, Fortec Motorsports, +0.901s
15. Leon Wilson, Arden Motorsport, +0.984s
16. Patricio Gonzalez, VRD Racing, +1.039s
17. Rodrigo Gonzalez, VRD Racing, +1.041s
18. Aurelia Nobels, Hillspeed, +1.243s
19. Yuhao Fu, Hitech, +1.304s
20. Ricardo Baptista, Xcel Motorsport, +1.387s
21. Nadeem Rustombi, VRD Racing, +2.568s*
*Testing, not racing this weekend