Nitrous Competitions ADM Racing's Luke Hilton topped two of Thursday's three GB4 sessions at Silverstone to end the first day of testing fastest overall.
Having set the quickest time in session one this morning, he found a tenth and a half to go quicker in session two, with his 2m02.528s being the lap to beat.
Hillspeed's Enzo Hallman was the other driver to top a session on Thursday, with his 2m02.818s enough to put him fastest in session three, and second overall on the combined times for the day.
Douglas Motorsport's Conor Grant, who was second fastest in the final session was third overall, just five thousandths of a second further back and 0.170s clear of KMR Sport's championship leader Alex O'Grady, another to set their best lap in the final session.
O'Grady's nearest title rival Fred Green put his Elite Motorsport machine fifth thanks to his session two lap, 0.024s behind and 0.170s clear of Fortec's Thomas Ingram Hill.
The second Douglas Motorsport car of Dayton Coulthard was next up in seventh overall, a scant one thousandth ahead of Fortec's Franciszek Cegielski, with Torrin Byrne (Pace) and Emmilio Valentino Del Grosso (Elite) completing the Thursday top-10, which was covered by 0.980s.
A total of 29 drivers took part in the test, with newcomers Faris Organji (Scorpio) and William Rohan (Arden) 21st and 24th respectively.
Testing at Silverstone resumes tomorrow with three more sessions.
GB4 Championship, partnered by the BRDC, Silverstone Thursday combined testing result:
1. Luke Hilton, Nitrous Competitions ADM Racing, 2m02.528s
2. Enzo Hallman, Hillspeed, +0.290s
3. Conor Grant, Douglas Motorsport, +0.295s
4. Alex O'Grady, KMR Sport, +0.465s
5. Fred Green, Elite Motorsport, +0.489s
6. Thomas Ingram Hill, Fortec Motorsports, +0.659s
7. Dayton Coulthard, Douglas Motorsport, +0.690s
8. Franciszek Cegielski, Fortec Motorsports, +0.691s
9. Torrin Byrne, Pace Performance, +0.774s
10. Emmilio Valentino Del Grosso, Elite Motorsport, +0.980s
11. Connor Willis, Hillspeed, +1.124s
12. Matan Achituv, Elite Motorsport, +1.192s
13. John O'Donnell, Pace Performance, +1.313s
14. Demitri Nolan, Hillspeed, +1.362s
15. Archie Davies, Scorpio Motorsport, +1.383s
16. Archie Bullard, Fox Motorsport, +1.435s
17. Michael Koh, Arden Motorsport, +1.543s
18. Joshua McLean, Pace Performance, +1.919s
19. Jordyn Martin, Fortec Motorsports, +2.003s
20. Jamie Leverton, Nitrous Competitions ADM Racing, +2.064s
21. Faris Organji, Scorpio Motorsport, +2.341s
22. Lily-May Watkins, KMR Sport, +2.485s
23. Solenn Amrouche, Arden Motorsport, +3.008s
24. William Rohan, Arden Motorsport, +3.191s
25. Caitlyn McDaniel, Nitrous Competitions ADM Racing, +3.214s
26. Jasser Iskander, Fox Motorsport, +3.291s
27. Holly Miall, KMR Sport, +3.368s
28. Romuald Bocquet, Scorpio Motorsport, +3.624s
29. Enzo Rujugiro, Fox Motorsport, +3.951s
