|British Grand Prix on the BBC|
|Venue: Silverstone Dates: 3 July to 5 July|
|Coverage: Live on BBC TV, Red Button, Radio 5 live, 5 live sports extra, online, mobile, the BBC Sport app and Connected TV. Full details here|
Mercedes driver Lewis Hamilton says he is "in trouble" at this weekend's British Grand Prix if he does not find a way to improve his car.
Hamilton was fourth fastest in Friday's second practice, nearly half a second behind team-mate Nico Rosberg, who set the pace ahead of both Ferraris.
Asked how much more he had to come, Hamilton said: "Hopefully a lot because if there is not then we are in trouble.
"It's been OK, but not the easiest of days. We have a bit of work to do."
World champion Hamilton was even further behind Rosberg when running in race trim with a heavy fuel load in the session, and actually abandoned that run to return to the garage.
"The long-run pace was not so great," Hamilton said. "I have to sit down and work out where it is. It is a general balance thing that we have to get right."
Even Rosberg said he was "not that happy" with his car, despite lapping 0.347secs faster than Ferrari's Kimi Raikkonen, who was 0.02secs quicker than team-mate Sebastian Vettel.
But Rosberg said he did not expect Hamilton's problems to have an effect on the world champion's competitiveness.
"I don't know what he did on his lap, so it's not representative," the German said. "It's close and I need to do my homework tonight."
|"Silverstone is one of the few truly iconic venues still surviving on a Formula 1 calendar increasingly dominated by antiseptic modern autodromes.|
|"Although comprehensively revised and updated for the 21st century, Silverstone is still recognisably the same place that hosted the very first F1 world championship race in 1950.|
|"And in the Becketts complex of sweepers and the ultra-fast Copse, it has some of the greatest corners on any race track anywhere in the world. To stand and watch there is to be awed by the capabilities of the cars and the skills and bravery of their drivers.|
|"The British crowd is as enthusiastic and knowledgeable as you will find and the ingredients add up to one of the best weekends of the season, no matter what the weather." Andrew Benson|
Rosberg said he was not that happy with his car's balance either.
"The car was a bit all over the place still," Rosberg said. "I think it was the track out there that was really difficult, especially as it was a lot hotter now than it will be on Sunday for the race.
"So we need to be careful with that. The balance that was good today will not be good for Sunday by far, so that is where the difficulties come in and you really need to think ahead. But I think it was valuable today and learned a lot of things."
Despite the Mercedes' drivers concerns, Vettel said he expected the world champions to be untouchable in qualifying, which is on Saturday at 1300 BST.
"I don't know if Mercedes had an issue but I don't think so," Vettel said. "I think tomorrow they will be very quick, we know they do a massive step from Friday to Saturday."
Silverstone hosted a huge 85,000 fans for Friday practice and there were some problems with traffic jams in the morning as a result of through traffic ignoring signs diverting them from the main A43 artery into the track.
There were also log-jams at the entry to campsites as more fans than expected turned up on Friday morning, perhaps as a result of the good weather.
A Silverstone spokeswoman said the track was not expecting similar problems over the weekend, even though 105,000 fans are due at the track for qualifying and a sell-out 140,000 for the race on Sunday.