SILVERSTONE, England (AP) Lewis Hamilton said he would gain very little from access to Mercedes team-mate Nico Rosberg's data after the driver topped the times but then stopped on track in Friday's practice for the British Grand Prix.
The 29-year-old Briton, champion in 2008 and desperate to win this Sunday's race to reboot his title bid this season, missed the final half hour of the afternoon's second free session while Rosberg ran without problems.
Hamilton, 29 points behind German Rosberg in the title race, had an engine problem that left him stranded out on the circuit.
Amid speculation that the two rivals and team-mates share little data within the team, Hamilton made clear that full access to Rosberg's information would be of little use.
Hamilton said: ''The long run data doesn't really help in the sense that we drive so differently. It doesn't help you in the sense of understanding how the tires are lasting, and whether you need to put the car into more understeer, or oversteer, whether you need to move the brake balance, or which corners you want to lift and coast.
''All those different things you need to practice. It makes it really hard, but I'll be OK. I don't know why things happen to my car so much. We'll fix it, but I really needed a long run. Now I don't know what the car is going to feel like for the race.''
Rosberg played down suggestions that the two were not sharing their information. ''We have to think about the team in the first instance and everything is open,'' he said.
''We share everything. We're dominating the sport because we've managed to work together really well. Of course, there comes a point where I am fighting him and at that point I will try to keep certain advantages, as he will too.
''We always try to keep an advantage over each other, but never compromising the team as a whole. It's a fine line.''
Hamilton had clocked a best lap in 1 minute, 34.508 seconds to outpace Rosberg by 0.228 seconds on a warm and windy day that saw two-time champion Spaniard Fernando Alonso third quickest for Ferrari.
Alonso was 0.7 seconds down on the pace-setters, but ahead of the two Red Bulls of Australian Daniel Ricciardo and defending four time champion German Sebastian Vettel.
They were both more than a second behind on sheer single lap pace, but improved their overall pace on the long runs in the final stages of the long afternoon session.
Hamilton came to a halt on track with a serious engine problem an hour into the 90-minutes session when he stopped out on the circuit. ''Engine stopped,'' he told the team by radio. ''Says engine kill, no shifting.''
He managed only 14 completed laps compared to Rosberg's 35, an advantage for the championship leader that he may be able to exploit on Sunday.
Finn Valtteri Bottas was sixth fastest for Williams - having missed the morning session when his car was briefly run for just three laps by Susie Wolff, the first woman to take part in a Grand Prix for 22 years - ahead of Briton Jenson Button in the leading McLaren.
Danish rookie Kevin Magnussen was eighth fastest in the second McLaren ahead of Finn Kimi Raikkonen of Ferrari and 10th placed Frenchman Jean-Eric Vergne of Toro Rosso.
Rosberg had topped the times Friday morning ahead of Hamilton in an opening session where the main focus was on the luckless Wolff.
The 31-year-old Scot at least became the first woman to take part in a Grand Prix weekend since 1992, even if she lasted only three laps before her engine failed. Only a few minutes later her Williams team-mate Brazilian Felipe Massa crashed out of the session.