Colin Turkington topped British Touring Car free practice as the WSR BMWs dominated at Knockhill.
With rain arriving just ahead of the second session, the fastest laps came during the morning running.
Alain Menu (BMR Volkswagen CC) and Sam Tordoff's Triple Eight MG6 set the early pace in the first session, which got faster as the damp track dried.
Gordon Shedden (Dynamics Honda Civic Tourer) then moved to the top before championship leader Turkington's WSR BMW went fastest in the final 15 minutes. He was the only runner to go under the 52s barrier, with 51.870s.
Rob Collard underlined the 125i M Sport's pace around the tight Scottish circuit by going second fastest, but neither WSR driver will start from pole, no matter what happens in qualifying.
Turkington has an eight-place grid penalty for a clash with Matt Neal's Honda in race three at Snetterton, while Collard will have to start from the back for accumulating too many misdemeanours earlier in the season.
Despite problems in the morning, Jason Plato made it out in time to go third quickest in his Triple Eight MG6, just ahead of Shedden and the Eurotech Honda Civic hatchback of reigning champion Andrew Jordan.
Turkington was also fastest in the wet second session, setting a time of 56.484s, with Nick Foster this time being the driver to complete a WSR one-two.
Just as drivers started to switch from wet Dunlops to slicks, the rain returned, with the last significant improvement being Tordoff moving into third, ahead of Plato.
A spin at the hairpin by Neal then brought out the red flags and nobody improved after the session restarted.
Practice 1 Pos Driver Car Time Gap Laps 1. Colin Turkington WSR BMW 51.870s 28 2. Rob Collard WSR BMW 52.274s +0.404s 21 3. Jason Plato MG 52.372s +0.502s 22 4. Gordon Shedden Honda 52.484s +0.614s 28 5. Andrew Jordan Eurotech Honda 52.531s +0.661s 30 6. Sam Tordoff MG 52.559s +0.689s 27 7. Alain Menu BMR VW 52.565s +0.695s 25 8. Nick Foster WSR BMW 52.591s +0.721s 28 9. Rob Austin RAR Audi 52.675s +0.805s 28 10. Matt Neal Honda 52.749s +0.879s 25 11. Adam Morgan Ciceley Mercedes 52.776s +0.906s 32 12. Mat Jackson Motorbase Ford 52.787s +0.917s 26 13. Glynn Geddie UA Toyota 52.874s +1.004s 30 14. Jack Clarke Motorbase Ford 53.006s +1.136s 30 15. Fabrizio Giovanardi Motorbase Ford 53.070s +1.200s 26 16. Hunter Abbott RAR Audi 53.206s +1.336s 32 17. Martin Depper Eurotech Honda 53.230s +1.360s 32 18. Marc Hynes MG 53.281s +1.411s 34 19. Warren Scott BMR VW 53.334s +1.464s 28 20. Tom Ingram Speedworks Toyota 53.427s +1.557s 26 21. Aron Smith BMR VW 53.519s +1.649s 32 22. Dave Newsham AmD Ford 53.569s +1.699s 26 23. Aiden Moffat Moffat Chevrolet 53.703s +1.833s 30 24. Lea Wood Houseman Toyota 53.865s +1.995s 27 25. Jack Goff BMR VW 53.887s +2.017s 17 26. Simon Belcher Handy Toyota 54.061s +2.191s 29 27. James Cole UA Toyota 54.074s +2.204s 28 28. Chris Stockton BTC Chevrolet 54.146s +2.276s 29 29. Robb Holland Rotek Audi 54.429s +2.559s 20 30. Ollie Jackson Welch Proton 54.995s +3.125s 23 31. Dan Welch Welch Proton 57.900s +6.030s 5 Practice 2 Pos Driver Car Time Gap Laps 1. Colin Turkington WSR BMW 56.484s 11 2. Nick Foster WSR BMW 56.506s +0.022s 10 3. Sam Tordoff MG 56.839s +0.355s 19 4. Jason Plato MG 56.902s +0.418s 13 5. Gordon Shedden Honda 57.112s +0.628s 14 6. Matt Neal Honda 57.200s +0.716s 16 7. Rob Austin RAR Audi 57.283s +0.799s 18 8. Andrew Jordan Eurotech Honda 57.354s +0.870s 10 9. Fabrizio Giovanardi Motorbase Ford 57.406s +0.922s 17 10. Rob Collard WSR BMW 57.418s +0.934s 18 11. Marc Hynes MG 57.428s +0.944s 16 12. Jack Goff BMR VW 57.442s +0.958s 23 13. Dave Newsham AmD Ford 57.622s +1.138s 13 14. Mat Jackson Motorbase Ford 57.835s +1.351s 16 15. Hunter Abbott RAR Audi 57.875s +1.391s 17 16. Simon Belcher Handy Toyota 57.876s +1.392s 15 17. Adam Morgan Ciceley Mercedes 57.914s +1.430s 21 18. Alain Menu BMR VW 57.927s +1.443s 14 19. Chris Stockton BTC Chevrolet 58.004s +1.520s 19 20. Glynn Geddie UA Toyota 58.086s +1.602s 20 21. Warren Scott BMR VW 58.159s +1.675s 13 22. Jack Clarke Motorbase Ford 58.343s +1.859s 12 23. Lea Wood Houseman Toyota 58.412s +1.928s 16 24. Martin Depper Eurotech Honda 58.607s +2.123s 18 25. Chris Stockton BTC Chevrolet 58.687s +2.203s 18 26. James Cole UA Toyota 59.094s +2.610s 18 27. Robb Holland Rotek Audi 59.149s +2.665s 17 28. Ollie Jackson Welch Proton 59.241s +2.757s 12 29. Aiden Moffat Moffat Chevrolet 59.377s +2.893s 16 30. Dan Welch Welch Proton 59.508s +3.024s 5