Lewis Hamilton admits the F1 teams are no closer to learning who is on top despite Friday's two practice sessions in Bahrain.
Unlikely last year's pre-season tests where Brawn GP emerged as the leading contender, this season none of the teams dominated, although it did appear as if McLaren and old rivals Ferrari had the better packages.
However, the story took a twist in Bahrain on Friday as the teams got down to serious business.
Friday's first session saw Adrian Sutil set the pace ahead of Ferrari and McLaren while Robert Kubica was also in the mix for Renault.
However, the second session had Nico Rosberg on top ahead of Hamilton and Michael Schumacher while this time Red Bull and Williams joined the party.
And although Hamilton admits that it was good opening day for McLaren, he insists he's still in the dark about who really is on top.
"It doesn't feel too bad for the first day out. I still don't have an understanding of where everyone else is, but on the track for us it's very hot so the degradation of both compounds of the tyres is very high," he said.
"On the lighter to heavier fuel loads the car feels pretty similar, but it's difficult to know where everyone is at the minute. You see the positions at the moment but it doesn't really correlate too much."
Asked what it feels like to drive the car with a full tank of fuel, Hamilton said: "It's a bit of a dog.
"It's very heavy, a bit like driving a bus I guess - it doesn't want to stop under braking. Through the high-speed corners it's quite well balanced with high fuel, it just doesn't stop as well."
But even though qualifying will take place on light fuel loads, the McLaren driver has downplayed his chances of putting his MP4-25 on pole position in Saturday's qualifying.
"I honestly have absolutely no clue. My car feels okay, but I don't know what everyone else is doing," he said.
"Some people might be heavier, some might be lighter. We might be seriously slow or we might be seriously quick, we just won't know until we go into qualifying tomorrow."
