Marco Sorensen topped the second day of Formula Renault 3.5 testing at Barcelona on Wednesday
The Dane, who finished sixth in the series for Lotus this season, stayed with the team for the two-day test.
His best time of the day came in the morning session, when track conditions were better and all but one of the 25 runners set their fastest times.
"I ended the season with a retirement so it's been a real boost for me to have two days of testing straightaway," said Sorensen.
"In my head I'm already in 2013, and the aim is to compete in Formula Renault 3.5 again. Over these two days we've been able to identify what had been bothering us in the last few races."
GP2 race winner Marcus Ericsson was just 0.010s adrift of Sorensen's best in second place, while Arthur Pic completed a promising first test for new team AV Formula by going third quickest overall, and leading the way in the slower afternoon session.
British F3 racers Carlos Sainz Jr and Jazeman Jaafar were fourth and sixth for Carlin, either side of the team's 2012 FR3.5 driver Will Stevens, who was out with DAMS.
Notable drivers getting their first taste of FR3.5 machinery on day two included new Formula Renault Eurocup champion Stoffel Vandoorne (18th with Arden Caterham), and Formula 2 frontrunner Matheo Tuscher (21st with Pons).
The latter - aged just 15 - is the youngest driver to ever get behind the wheel of one of the Renault machines.
Pos Driver Team Time Gap 1. Marco Sorensen Lotus 1m28.971s 2. Marcus Ericsson P1 1m28.981s + 0.010s 3. Arthur Pic AV 1m29.009s + 0.038s 4. Carlos Sainz Jr Carlin 1m29.185s + 0.214s 5. Will Stevens DAMS 1m29.263s + 0.292s 6. Jazeman Jaafar Carlin 1m29.283s + 0.312s 7. Pietro Fantin Lotus 1m29.376s + 0.405s 8. Andre Negrao Draco 1m29.488s + 0.517s 9. Sergey Sirotkin ISR 1m29.493s + 0.522s 10. Norman Nato Arden Caterham 1m29.569s + 0.598s 11. Tamas Pal Kiss BVM Target 1m29.727s + 0.756s 12. Kevin Magnussen Fortec 1m29.733s + 0.762s 13. Will Buller Comtec 1m29.845s + 0.874s 14. Nikolay Martsenko Tech 1 1m29.872s + 0.901s 15. Conor Daly Tech 1 1m30.007s + 1.036s 16. Christopher Zanella Comtec 1m30.038s + 1.067s 17. Vittorio Ghirelli Draco 1m30.125s + 1.154s 18. Stoffel Vandoorne Arden Caterham 1m30.156s + 1.185s 19. Zoel Amberg Pons 1m30.169s + 1.198s 20. Yann Cunha AV 1m30.473s + 1.502s 21. Matheo Tuscher Pons 1m30.712s + 1.741s 22. Lucas Foresti Fortec 1m30.725s + 1.754s 23. Matias Laine DAMS 1m31.279s + 2.326s 24. Filip Salaquarda ISR 1m31.368s + 2.397s 25. Ignazio d'Agosto BVM Target 1m31.997s + 3.026s
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