Red Bull junior drivers Carlos Sainz Jr. and Daniil Kvyat topped the first day of testing with the new GP3 car at Estoril on Wednesday.
The MW Arden teammates led the way ahead of morning pacesetter Tio Ellinas, as the new car went more than three seconds faster than its predecessor had ever managed at the Portuguese track.
Formula Renault ALPS champion Kvyat topped the order heading into the closing stages, as the times tumbled in the afternoon after a morning where only around half of the field set a representative lap time.
Ellinas, who went nearly two seconds quicker than his morning benchmark, narrowly missed out on heading the Russian, before Sainz blitzed the field with 15 minutes to go.
"So many people had said how difficult the new car would be to drive and they were right," said Sainz. "I was so surprised with the amount of power and the speed through the corners. We had a great base to start with so we will see what we can achieve."
Trident's David Fumanelli made sure the top four drivers from the morning stayed at the front in the afternoon, just ahead of Formula Renault 3.5 convert Kevin Korjus and the third MW Arden car of Robert Visoiu.
GP2 and GP3 technical director Didier Perrin was pleased with the opening day for the new GP3/13, and he believes it will produce more spectacular racing when the season kicks off.
"Today has been a big success," he said. "With more power, the car will be much more demanding for drivers. Therefore I am very confident that when we arrive in Barcelona for the first round, we will produce an even better show and a high level of exciting competition."
Pos Driver Team Time Laps
1. Carlos Sainz Jr MW Arden 1m26.816s 29
2. Daniil Kvyat MW Arden 1m27.616s 27
3. Tio Ellinas Manor 1m27.681s 19
4. David Fumanelli Trident 1m27.714s 26
5. Kevin Korjus Koiranen 1m27.846s 25
6. Robert Visoiu MW Arden 1m27.871s 24
7. Giovanni Venturini Trident 1m28.021s 30
8. Patric Niederhauser Jenzer 1m28.068s 42
9. Facu Regalia ART 1m28.112s 27
10. Conor Daly ART 1m28.309s 28
11. Jack Harvey ART 1m28.509s 21
12. Patrick Kujala Koiranen 1m28.614s 24
13. Aaro Vainio Koiranen 1m28.791s 19
14. Alex Fontana Jenzer 1m28.844s 28
15. Nick Yelloly Carlin 1m29.019s 28
16. Adderly Fong Status 1m29.029s 26
17. Emanuele Zonzini Trident 1m29.159s 28
18. Dino Zamparelli Manor 1m29.201s 30
19. Josh Webster Status 1m29.417s 27
20. Samin Gomez Jenzer 1m29.682s 35
21. Vicky Piria Manor 1m29.816s 27
22. Eric Lichtenstein Carlin 1m29.852s 27
23. Ethan Ringel Bamboo 1m30.266s 27
24. Luis Sa Silva Carlin 1m30.477s 26
25. Jimmy Eriksson Status 1m30.694s 29
26. Lewis Williamson Bamboo 1m31.142s 9
27. Roberto La Rocca Bamboo 1m31.313s 13