Alain Menu led a Chevrolet one-two-three in the half-hour World Touring Car Championship test at Curitiba on Friday.
The Swiss racer produced a time of 1m22.743s in the final minute to edge out long-time pacesetter Rob Huff by 0.173 seconds.
Reigning world champion Yvan Muller was a close third, 0.027s behind the Briton.
The performance indicated that despite Chevrolet recently announcing its factory withdrawal from the WTCC at the end of the season, the RML-prepared cars are unlikely to suffer any drop-off in form.
Lukoil SEAT driver Gabriele Tarquini was top non-Chevrolet runner in fourth. The Italian, who confirmed his switch to the factory Honda WTCC team for 2013 this week, was over a second adrift of Menu.
The Bamboo Chevrolet Cruzes had an encouraging showing to round out the top six. WTCC rookie Alex MacDowall claimed fifth spot ahead of new team-mate, Swedish series frontrunner and WTCC returnee, Michel Nykjaer.
Dane Nykjaer is substituting for Bamboo's regular driver Pasquale di Sabatino, who the team reported is recovering from bronchitis and pneumonia.
Tom Coronel took top BMW honours for ROAL Motorsport in seventh, ahead of Salzburging reversed-grid winner Stefano D'Aste.
Pos Driver Team/Car Time Gap 1. Alain Menu Chevrolet 1m22.743s 2. Robert Huff Chevrolet 1m22.916s + 0.173s 3. Yvan Muller Chevrolet 1m22.943s + 0.200s 4. Gabriele Tarquini Lukoil SEAT 1m23.572s + 0.829s 5. Alex MacDowall Bamboo Chevrolet 1m23.769s + 1.026s 6. Michel Nykjaer Bamboo Chevrolet 1m24.261s + 1.518s 7. Tom Coronel ROAL BMW 1m24.521s + 1.778s 8. Stefano D'Aste Wiechers BMW 1m24.561s + 1.818s 9. Tiago Monteiro Tuenti SEAT 1m24.934s + 2.191s 10. Tom Chilton Arena Ford 1m25.105s + 2.362s 11. Norbert Michelisz Zengo BMW 1m25.130s + 2.387s 12. Alberto Cerqui ROAL BMW 1m25.187s + 2.444s 13. Darryl O'Young Special Tuning SEAT 1m25.274s + 2.531s 14. Aleksei Dudukalo Lukoil SEAT 1m25.414s + 2.671s 15. Mehdi Bennani Proteam BMW 1m25.765s + 3.022s 16. Franz Engstler Engstler BMW 1m25.861s + 3.118s 17. James Nash Arena Ford 1m25.899s + 3.156s 18. Charles Ng Engstler BMW 1m26.406s + 3.663s 19. Tom Boardman Special Tuning SEAT 1m26.462s + 3.719s 20. Pepe Oriola Tuenti SEAT 1m27.255s + 4.512s 21. Fernando Monje SUNRED SEAT 1m28.023s + 5.280s