Barcelona F1 test: Lewis Hamilton puzzled by Mercedes set-up

Mercedes' pace has shocked F1 rivals at the Barcelona circuit this week, but both drivers have complained about the set-up of the car.

Hamilton spent much of his final day of pre-season testing in the garage while Mercedes crosschecked changes to the car, but he still managed to top the times.

The reigning world champion suspected a shift in circuit conditions might account for the drivers' discomfort, but he said the team was investigating.

"It wasn't particularly a spectacular day," Hamilton said. "I put the lap together, but the track was quite slow compared to the first day.

"We're trying to understand. All of a sudden the car was feeling worse than my first day and we made some changes to understand why, whether something's happened with the track or the tyres.

"The track seems to have lost some grip from the last two days, so it wasn't the best in terms of feeling.

"Nico wasn't comfortable in the car yesterday and I felt the same.

"We think the tyres and the circuit are behaving a little differently these last two days, and we think the track's been half a second to seven tenths slower than the first day."

ILLNESS NO SETBACK

A fever sidelined Hamilton from his first day of driving at last week's Barcelona test, but the Briton said the after effects would not affect his preparations for the season-opening Australian Grand Prix.

"I should be fine," he added. "The bug's been around - my mum, my sister, my nephew, several of my engineers have it.

"It's just some nasty bug that's going around. I'm kind of on the end of having it, so it hasn't really affected preparations."