Silverstone: World champion Sebastian Vettel lapped fastest in final British Grand Prix practice Saturday while Red Bull team bosses spent most of the session arguing with officials over yet another rule revision.
After rain washed out much of Friday`s running, the German made the most of drier conditions to set a best time of one minute 31.401 seconds.
Ferrari`s double world champion Fernando Alonso was second on the timesheets, 0.063 slower, with Red Bull`s Australian Mark Webber -- last year`s race winner -- in third place.
McLaren`s Lewis Hamilton was 13th and team mate Jenson Button, who has never stood on his home podium as an F1 driver, sixth.
At the slow end, Australian debutant Daniel Ricciardo lapped faster than Italian team mate Vitantonio Liuzzi in the Hispania.
Vettel will be chasing his third successive British Grand Prix pole in qualifying later Saturday and his eighth in nine races this year.
The Red Bull`s continuing speed was some consolation for team boss Christian Horner, who spent the best part of an hour with technical head Adrian Newey locked in talks with race director Charlie Whiting.
The meeting followed yet another directive from the governing International Automobile Federation (FIA) about the engine regulations and sent to all the teams Saturday morning.
In it, according to a copy pinned on the notice board next to race control, the FIA effectively backtracked on one sent out the previous day which had drawn complaints from Mercedes-powered McLaren.
Horner and Newey refused to comment after the meeting, leaving stony-faced and stalking back down the paddock to the Red Bull garages.
The FIA is clamping down on the use of exhaust gases for performance gain through engine maps that keep the throttle open even when a driver is braking to ensure a steady flow through the rear of the car.
Friday`s directive had allowed Renault to keep the engine throttle 50 percent open, on grounds of reliability, while Mercedes were allowed to retain other characteristics of their engine.
However, sources said the FIA had decided Saturday to revert to a previous position and reduce Renault`s allowance to 10 percent at 12,000 revs and 20 percent at the maximum 18,000 revs.
The French manufacturer also supplies Renault and Team Lotus as well as Red Bull.