Hitech Pulse-Eight's Gerrard Xie ended Thursday testing by setting the quickest time of the day in the final session.
The Chinese driver registered a best time of 1m23.088s to top the times by over a quarter of a second from Elite's McKenzy Cresswell, with JHR's John Bennett just 0.036s further back.
It was even closer behind, as Rodin's championship leader Louis Sharp was just one thousandth of a second further back, and 0.020s clear of Arden's impressive newcomer Max Taylor in fifth.
Hitech's Will Macintyre completed the session three top-six, a tenth clear of Elite's Jarrod Waberski, with Colin Queen (Fortec), another debutant in the form of Rodin's Freddie Slater, and Elite's Hugo Schwarze completing the session three top-10, which was covered by 0.724s.
Xie's session three time was enough for him to top the combined times for the day, having also led session one. Xie was the only driver in the top five to record their best time in the final session, with Sharp, Queen, Tymek Kucharczyk (Hitech) and Macintyre all recording their best efforts this morning.
Cresswell's session three lap put him sixth overall, ahead of Bennett (session one) and Waberski, who was quickest in session two.
Taylor and VRD Racing by Arden's Noah Ping completed the combined top-10, with just three tenths of a second splitting them.
The top-17 on Thursday were covered by under a second, and all 21 cars in action today were within 1.5 seconds of the pace.
Testing resumes at Donington Park tomorrow.
GB3 Championship, partnered by the BRDC, Donington Park Thursday testing combined times:
1. Gerrard Xie, Hitech Pulse-Eight, 1m23.088s
2. Louis Sharp, Rodin Motorsport, +0.117s
3. Colin Queen, Fortec Motorsport, +0.151s
4. Tymek Kucharczyk, Hitech Pulse-Eight, +0.154s
5. Will Macintyre, Hitech Pulse-Eight, +0.223s
6. McKenzy Cresswell, Elite Motorsport, +0.242s
7. John Bennett, JHR Developments, +0.255s
8. Jarrod Waberski, Elite Motorsport, +0.282s
9. Max Taylor, Arden Motorsport, +0.299s
10. Noah Ping, VRD Racing by Arden, +0.325s
11. Patrick Heuzenroder, JHR Developments, +0.388s
12. Arthur Rogeon, Rodin Motorsport, +0.415s
13. Freddie Slater, Rodin Motorsport, +0.550s
14. Hugo Schwarze, Elite Motorsport, +0.607s
15. Nikita Johnson, VRD Racing by Arden, +0.700s
16. Seb Murray, Chris Dittmann Racing, +0.846s
17. Josh Irfan, JHR Developments, +0.998s
18. Shawn Rashid, VRD Racing by Arden, +1.020s
19. Alex Kattoulas, Fortec Motorsport, +1.061s
20. Flynn Jackes, Chris Dittmann Racing, +1.181s
21. Jacob Douglas, Chris Dittmann Racing, +1.509s