Seven pole positions in the last eight grands prix and three wins in the last five have made Mercedes the main challengers to Red Bull.
Heading into the summer break, Mercedes driver Lewis Hamilton trails Red Bull's championship leader Sebastian Vettel by 48 points, with Mercedes 69 adrift of the reigning champions in the constructors' race.
While the Mercedes appears to have become the car to beat, team principal Brawn knows they have been "far from perfect" so far.
"The first half of this season can be split into two halves again - the first five races and the second five races," Brawn told the team's YouTube channel.
"I'm very pleased particularly with the second five races because we have started to pick up some momentum, pick up some strength.
"We're starting to convert the pole positions into race results, winning three of the last five races, but we're far from perfect. We've still a lot to do, but the momentum we've got going into the second half of the season is really strong."
With one eye on the crucial development of next year's car, the challenge is to balance resources.
"It's our big challenge to maintain our form, and a tough challenge with the demands of next season as well. Balancing those two things out is going to be tricky," said Brawn.
"But the team has great spirit at the moment, and I know the things which are coming through on the technical front.
"Our hit rate has been pretty good on new technical innovations this year. Things we've brought to the track have generally worked.
"We have some things coming through at the next few races which could give us that extra impetus, that extra momentum to take us through the second half of the year."
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