Mat Jackson continued his excellent recent form by setting the pace in British Touring Car Championship practice at Rockingham.
The RML Chevrolet driver, who won twice at Silverstone, was only sixth fastest in the morning session, but improved as the track temperature increased in the afternoon to lap in 1m24.200s.
His lap was 0.031s quicker than Motorbase BMW driver Jonathan Adam managed on his way to topping the morning session. Adam was second quickest overall, but only 0.016s up on the similar WSR-run car of Stephen Jelley.
Fourth quickest was Matt Neal in the best of the Vauxhalls. But the two-time champion's second session came to an abrupt end when he locked his rear brakes coming into the Deene hairpin, his Vectra sliding into the retaining wall and causing damage to the front-right corner.
His teammate Fabrizio Giovanardi was next up, significantly four tenths of a second - and four places - up on the WSR BMW of Colin Turkington, the man he trails by nine points in the championship hunt.
Between them were Tom Chilton (Arena Ford), Jason Plato (RML Chevy) and Andrew Jordan, who also ended his session early when the Vauxhall team detected a strange noise coming from the transmission on his Vectra.
Former grand prix winner Johnny Herbert was 16th quickest and a second off the pace in his Team Dynamics Honda, while BTCC debutant Matt Hamilton was 19th in his 2002-spec TH Motorsport Honda Civic.
There were also problems for Hamilton's team-mate, John George, who lost a damper bearing on his front-right wheel during the afternoon, and for Martin Johnson, who missed the morning session because third and fourth gears had been installed the wrong way round in his Boulevard Vauxhall.
Combined practice times:
Pos Driver Car Time
1. Mat Jackson Chevrolet 1m24.200s
2. Jonathan Adam BMW 1m24.231s
3. Stephen Jelley BMW 1m24.257s
4. Matt Neal Vauxhall 1m24.288s
5. Fabrizio Giovanardi Vauxhall 1m24.397s
6. Tom Chilton Ford 1m24.432s
7. Jason Plato Chevrolet 1m24.439s
8. Andrew Jordan Vauxhall 1m24.615s
9. Colin Turkington BMW 1m24.750s
10. Paul O'Neill Honda 1m24.843s
11. Rob Collard BMW 1m24.980s
12. Gordon Shedden SEAT 1m25.037s
13. Tom Onslow-Cole Ford 1m25.069s
14. Anthony Reid BMW 1m25.125s
15. Harry Vaulkhard Chevrolet 1m25.292s
16. Johnny Herbert Honda 1m25.362s
17. James Nash Chevrolet 1m25.381s
18. David Pinkney Honda 1m25.473s
19. Matt Hamilton Honda 1m27.245s
20. John George Honda 1m27.262s
21. Martin Johnson Vauxhall 1m27.607s