Coulthard was hoping for more speed

Although with a low load of fuel, the Red Bull Racing driver set the fastest time of the week in testing last week, and the Scot was expecting a step forward in this weekend's race.

Coulthard, however, was only 12th fastest in practice.

"Although you can't really tell too much from a Friday, I was perhaps hoping to show more solidly, relative to Renault and some of the other teams, today," said Coulthard.

"Looking at fuel levels, of course we've all got some fuel on board, but you don't know if any of the teams have gone for a low fuel run, so tomorrow will be the real test.

"Lots of people target Barcelona for upgrades, so if everyone ends up gaining the same amount, the status quo remains - we'll know more after qualifying."

Teammate Mark Webber wound up ninth after what he labelled as a "faultless" day.

"We got through most of the programme as planned today, which was good," he said. "We made the car more stable this afternoon, compared to the morning, and the track was better too.

"We have a lot of good data for tonight and it was a faultless programme from the guys. The mechanics worked bloody hard last night and all of today, and the entire team's working really well."