Tuesday 8 May at 07:35 : May 8 (GMM) Getting the setup right is a challenge teams are grappling with in 2012.

So far this season, four different cars have won the four grands prix, with Pirelli's difficult tyres credited or blamed for the unbalance of power.

The key, according to Mercedes team boss Ross Brawn, is car setup.

"We can't modify the setup between qualifying on Saturday and the race on Sunday," he is quoted by Brazil's O Estado de S.Paulo newspaper. "And they are very different challenges, especially with this year's tyres.

"It's one thing to get the car to be fast on one lap and quite another to make it fast and consistent over 70.

"Whoever can anticipate what will be required for the race and come to a compromise - maybe to the detriment of grid position - should have a decisive advantage in the race.

"But it's not easy to anticipate what happens on Sunday," insisted Brawn.