Elite Motorsport's title challenger Isaac Phelps started the Donington Decider weekend in ideal fashion by topping the first day of testing at the East Midlands circuit.
Phelps, who enters the weekend 21 points behind championship leader Dan Guinchard, recorded a best lap of 1m28.381s in session two, putting him over three tenths of a second clear of the field. In an extraordinarily close top-10, the next nine drivers were separated by little over a tenth of a second.
Arden's Leon Wilson was second fastest, also with his time from session two, and also topped the final session of the day by just 0.003s from Guinchard.
ADM's Jason Pribyl completed the day's top-three, just 0.013s behind and 0.017s ahead of Douglas Motorsport's Lucas Blakeley. Fortec's Jack Taylor and Pace Performance's Stefan Bostandjiev were within 0.005s of the Scotsman as they completed the top-six.
Championship contenders Alex Kattoulas (Elite) and Hillspeed's Guinchard were seventh and eighth, and set exactly the same time, with Kattoulas recording his best time in session two and Guinchard's in the final test.
Elite's Ary Bansal, yet another title challenger, was ninth, only 0.037s further back, and 0.007s ahead of Fortec's Thomas Ingram Hill, who completed a top-10 separated by just 0.432s.
KMR Sport's Alex O'Grady was the session one pace setter, with that time putting him 11th overall.
Testing at Donington Park continues tomorrow, with three further sessions ahead of the final rounds of the year.
GB4 Championship, partnered by the BRDC, Thursday testing combined result:
1. Isaac Phelps, Elite Motorsport, 1m28.381s
2. Leon Wilson, Arden Motorsport, +0.316s
3. Jason Pribyl, ADM, +0.329s
4. Lucas Blakeley, Douglas Motorsport, +0.346s
5. Jack Taylor, Fortec Motorsport, +0.348s
6. Stefan Bostandjiev, Pace Performance, +0.353s
7. Alex Kattoulas, Elite Motorsport, +0.388s
8. Dan Guinchard, Hillspeed, +0.388s
9. Ary Bansal, Elite Motorsport, +0.425s
10. Thomas Ingram Hill, Fortec Motorsports, +0.432s
11. Alex O'Grady, KMR Sport, +0.506s
12. Dayton Coulthard, Douglas Motorsport, +0.517s
13. Leandro Juncos, Hillspeed, +0.594s
14. Luca Magnussen, Fortec Motorsports, +0.799s
15. Ava Dobson, Arden Motorsport, +1.128s
16. Lewis Wherrell, KMR Sport, +1.303s
17. Flame Airikkala, Hillspeed, +1.450s
18. Enzo Hallman, Douglas Motorsport, +1.466s
19. Josh McLean, Pace Performance, +1.724s
20. Dudley Ruddock, Arden Motorsport, +2.201s
21. Holly Miall, Fox Motorsport, +2.275s
22. Lily May Watkins, KMR Sport, +2.385s
23. Caitlyn McDaniel, Fox Motorsport, +2.760s
24. John O'Donnell. Pace Performance, +3.060s
