Three of the team's Primera GTs were in the top five, with Anthony Reid heading the pack in a time of 44.531 seconds, just inside the Kent track's qualifying record.
"I was fastest in official testing at Donington, but it didn't happen for me there in the race," Reid said. "What we have learned is that the car is very well balanced."
Volvo's Rickard Rydell ran Reid the closest, while the championship leader, James Thompson, was third fastest in his Honda. An impressive fourth was Matt Neal, Nissan's runner in the Autosport Cup for Independents, with David Leslie in the works Primera completing the top five.
The Renault team suffered several problems, among them a lack of grip, as Jason Plato was seventh after two off-track excursions and the reigning champion, Alain Menu, finished 10th fastest.
The former Formula One world champion, Nigel Mansell, testing for Ford ahead of his British Touring Car Championship debut next month, was plagued by mechanical problems with his new Mondeo and could only record a best time of 45.807sec.