Douglas Motorsport's Conor Grant topped the times, as the Brands Hatch finale weekend got underway with four test sessions on the Indy circuit.
The Irish driver, who is still in contention for the Rookie Driver Title, posted a 45.020s effort in the first session of the day, which went unbeaten for the remainder of the afternoon.
He ended the day just nine thousandths of a second clear of Elite Motorsport's Matan Achituv, who also registered his best lap at the start of running.
Elite Motorsport's title contender Fred Green was quickest in session two, with that lap placing him third overall in the combined times for the day.
Fortec's title outsider Thomas Ingram Hill was 0.034s further back in fourth, and 0.030s clear of KMR Sport's championship favourite Alex O'Grady.
Ingram Hill's teammate Franciszek Cegielski, who is the lead Rookie driver heading into the final round, completed the top-six, which was covered by three tenths of a second.
Hillspeed's title aspirant Enzo Hallman was just 0.009s further back in seventh, and 0.010s clear of Elite Motorsport's Emmilo Valentino Del Grosso, with Pace Performance's John O'Donnell and Hillspeed's Connor Willis completing a top-10 covered by 0.426s.
Douglas Motorsport's title contender Dayton Coulthard was just outside the top-10, and 0.012s away from Willis.
The GB4 season finale weekend switches to the Grand Prix circuit for the rest of the event, with qualifying at 13.20 ahead of the first race of the weekend at 17.20.
GB4 Championship, partnered by the BRDC, Brands Hatch Indy Circuit, Friday combined test result:
1. Conor Grant, Douglas Motorsport, 45.020s
2. Matan Achituv, Elite Motorsport, +0.009s
3. Fred Green, Elite Motorsport, +0.195s
4. Thomas Ingram Hill, Fortec Motorsports, +0.229s
5. Alex O'Grady, KMR Sport, +0.259s
6. Franciszek Cegielski, Fortec Motorsports, +0.318s
7. Enzo Hallman, Hillspeed, +0.327s
8. Emmilio Valentino Del Grosso, Elite Motorsport, +0.337s
9. John O'Donnell, Pace Performance, +0.419s
10. Connor Willis, Hillspeed, +0.426s
Click to view full results.
