Daniel Welch's Proton was quickest in the second British Touring Car free practice session at Silverstone on Saturday.
Jason Plato (works MG6) and the Motorbase NGTC Ford Focus of Mat Jackson set the early pace on a dry track.
Jackson had got down to 59.324s before he lost control exiting Brooklands and hit the barriers on the entry to Luffield. The Ford limped back to the pits, but debris briefly brought out the red flags.
Plato immediately went quickest after the restart, only for Welch - whose Proton had been fast throughout the session - to top the times in the closing moments.
Behind Plato, Aron Smith was the only other driver to usurp Jackson's earlier mark, going third in one of Motorbase's S2000 Focuses.
Dave Newsham's ES Racing Vauxhall Vectra was fifth, while the pace of the WSR BMWs was underlined by all three cars being in the top 10.
As expected, the NGTC Honda Civics struggled on the straightline speed-dominated track. Reigning champion Matt Neal was the best in 12th, two spots behind the old S2000 Civic of Howard Fuller (Team Hard).
BTCC returnee Chris Stockton was 22nd of the 24 runners in Thorney Motorsport's Vauxhall Insignia.
Pos Driver Team/Car Time Gap 1. Daniel Welch Welch Proton 59.165s 2. Jason Plato MG 59.194s + 0.029s 3. Aron Smith Motorbase Ford 59.323s + 0.158s 4. Mat Jackson Motorbase Ford 59.324s + 0.159s 5. Dave Newsham ES Vauxhall 59.563s + 0.398s 6. Tom Onslow-Cole WSR BMW 59.602s + 0.437s 7. Rob Collard WSR BMW 59.608s + 0.443s 8. Frank Wrathall Dynojet Toyota 59.678s + 0.513s 9. Nick Foster WSR BMW 59.687s + 0.522s 10. Howard Fuller Gilham Honda 59.746s + 0.581s 11. Andy Neate MG 59.792s + 0.627s 12. Matt Neal Honda 59.904s + 0.739s 13. Adam Morgan Speddworks Toyota 59.916s + 0.751s 14. Will Bratt Austin Audi 59.935s + 0.770s 15. Gordon Shedden Honda 59.945s + 0.780s 16. Andrew Jordan Eurotech Honda 59.963s + 0.798s 17. Rob Austin Austin Audi 1m00.155s + 0.990s 18. Liam Griffin Motorbase Ford 1m00.206s + 1.041s 19. Chris James ES Vauxhall 1m00.235s + 1.070s 20. Lea Wood Wood Vauxhall 1m00.390s + 1.225s 21. Jeff Smith Eurotech Honda 1m00.575s + 1.410s 22. Chris Stockton Thorney Vauxhall 1m00.976s + 1.811s 23. Tony Hughes Speedworks Toyota 1m01.168s + 2.003s 24. Ollie Jackson AmD Volkswagen 1m07.020s + 2.201s