Jeroen Bleekemolen set the pace in the first A1GP practice session of the weekend at Brands Hatch on Friday.
The Dutch driver, who won on his last outing for the team at Kyalami in February, went to the top of the timesheet halfway through the session, and then continued to lower his time from there.
Adam Carroll made sure Ireland was the highest placed of the three title-chasing teams by moving up to second in the closing stages, half a second adrift of Bleekemolen.
Behind Carroll, Narain Karthikeyan - a winner at Brands last year - ran at the sharp end of the times all session, and eventually ended it in third place, ahead of Monaco's Clivio Piccione.
USA finished the session in fifth place as JR Hildebrand put in an impressive performance ahead of his race debut for the team. The Indy Lights driver was quickest in the early stages, before being shuffled back once Bleekemolen and the rest got up to speed.
Ireland's title rivals this weekend - Portugal and Switzerland – had a tougher session than they would have liked. While Filipe Albuquerque was sixth fastest, his session ended in the gravel trap thanks to an off at Sheene Curve in the final seconds of practice.
Switzerland made a low-key start to its weekend as it bids to retain the title with Neel Jani, as it ended the session in 10th place, just ahead of home driver Dan Clarke, who is racing at Brands for the first time since winning the 2004 Formula Ford Festival.
After his surprise pole position for his debut in Portugal last time out, ex-grand prix driver Vitantonio Liuzzi had a difficult time this afternoon. He had a low-speed spin coming out of Druids early on, then crashed when he ran wide at Stirlings later in the session.
In the earlier rookie sessions, Nicolas Prost was fastest for Team France. He carried that form into the main practice session, running near the front for most of it, before eventually dropping to seventh in the closing stages.
Pos Driver Team Time Gap
1. Jeroen Bleekemolen Netherlands 1m12.700s
2. Adam Carroll Ireland 1m13.203s +0.503
3. Narain Karthikeyan India 1m13.284s +0.584
4. Clivio Piccione Monaco 1m13.398s +0.698
5. JR Hildebrand USA 1m13.403s +0.703
6. Filipe Albuquerque Portugal 1m13.568s +0.868
7. Nicolas Prost France 1m13.592s +0.892
8. Earl Bamber New Zealand 1m13.892s +1.192
9. John Martin Australia 1m13.892s +1.192
10. Neel Jani Switzerland 1m13.991s +1.291
11. Dan Clarke Great Britain 1m14.046s +1.346
12. Franky Cheng China 1m14.220s +1.520
13. Daniel Morad Lebanon 1m14.227s +1.527
14. Michael Ammermuller Germany 1m14.280s +1.580
15. Salvador Duran Mexico 1m14.331s +1.631
16. Vitantonio Liuzzi Italy 1m14.598s +1.898
17. Alan van der Merwe South Africa 1m14.761s +2.061
18. Felipe Guimaraes Brazil 1m14.941s +2.241
19. Satrio Hermanto Indonesia 1m15.175s +2.475
20. Aaron Lim Malaysia 1m15.309s +2.609