Emil Bernstorff ended pre-season GP3 testing on top as he set the fastest time for Carlin at Barcelona on Thursday.
The Briton outpaced Jenzer's Pal Varhaug by 0.205 seconds in the quicker morning session.
"I just had a lap where I put everything together and didn't make any mistakes," said Bernstorff.
"The car feels really good, and it's a nice confidence boost to finish the final test quickest, particularly at the track we'll race on first."
Bernstorff's team-mate and Red Bull junior Alex Lynn completed the top three, with day one pacesetter Nick Yelloly making it three Brits in the top four places.
Another Brit hit the front in the afternoon, when Dean Stoneman was fastest for the Marussia Formula 1-affiliated Manor team, although times for the whole field were a long way adrift of the morning.
Varhaug was second again, with rookie Roman de Beer third for Trident.
Three red flags affected the running, caused by incidents for Denis Nagulin and Victor Carbone, and Patric Niederhauser coming to a halt on the circuit.
The 2014 GP3 driver line-up also took a step closer to completion on Thursday when Koiranen announced that it had signed Carmen Jorda for her third season in the category.
The GP3 season starts as part of the Spanish Grand Prix support bill at Barcelona in three weeks' time.
Pos Driver Team Time Gap Laps
1. Emil Bernstorff Carlin 1m34.494s 62
2. Pal Varhaug Jenzer 1m34.699s +0.205s 65
3. Alex Lynn Carlin 1m34.727s +0.233s 62
4. Nick Yelloly Status 1m34.754s +0.260s 64
5. Patric Niederhauser Arden 1m34.845s +0.351s 69
6. Luis Sa Silva Carlin 1m34.897s +0.403s 58
7. Alex Fontana ART 1m34.908s +0.414s 79
8. Marvin Kirchhofer ART 1m34.981s +0.487s 79
9. Jimmy Eriksson Koiranen 1m35.096s +0.602s 60
10. Patrick Kujala Manor 1m35.114s +0.620s 59
11. Dino Zamparelli ART 1m35.144s +0.650s 73
12. Adderly Fong Jenzer 1m35.171s +0.677s 62
13. Santiago Urrutia Koiranen 1m35.282s +0.788s 61
14. Matheo Tuscher Jenzer 1m35.305s +0.811s 60
15. Dean Stoneman Manor 1m35.353s +0.859s 63
16. Roman de Beer Trident 1m35.398s +0.904s 65
17. Jann Mardenborough Arden 1m35.572s +1.078s 74
18. Robert Visoiu Arden 1m35.693s +1.199s 65
19. Richie Stanaway Status 1m35.839s +1.345s 55
20. Alfonso Celis Jr Status 1m36.165s +1.671s 70
21. Ryan Cullen Manor 1m36.312s +1.818s 50
22. Nelson Mason Hilmer 1m36.334s +1.840s 58
23. Victor Carbone Trident 1m36.620s +2.126s 66
24. Ivan Taranov Hilmer 1m37.211s +2.717s 71
25. Denis Nagulin Trident 1m37.296s +2.802s 70
26. Carmen Jorda Koiranen 1m39.117s +4.623s 33