Interlagos. A circuit of contrasting extremes.

The brazilian circuit has the shortest lap time of the season. Interlagos is a circuit of extremes, combining slow hairpins with a long straights. The physical demands of this bumpy circuit are intensified by the fact that it runs anti-clockwise, subjecting the drivers necks to the opposite loadings experienced at a normal clockwise track.
Let´s see the key features to turn a good lap in Interlagos:

Engine: Because of the lost of power caused by the altitude of the circuit (around 7%) and a long main straight (some part in uphill), the engines are crucial to turn a good lap time.
Aerodinamics: In Interlagos is desired high aerodinamic pressure in the middle of circuit (second sector) and a low aerodinamic pressure in the other two sectors to reach higher speeds. One solution for this extremes is to set a high aerodinamic pressure in the front wing  to combat the understeer in the middle of the circuit, and low aerodinamic pressure in the rear wing to reduce drag and reach high speeds. It happens because the impact of high pressure of the rear wing over the maximum speed of the car is bigger than in the front wing.
Suspension: It's always important. In Interlagos the mechanical grip is important in the second sector of the track to compensate the oversteer caused by the low aerodinamic pressure in the rear.
Gearbox: medium to high acceleration, it's necessary short gears for the first 5 gears because of the slow second sector and to take a good reponse in the exit of the uphill Junção curve.
Brakes: brakes aren't the problem in Interlagos.

More information to build a car setup for Interlagos can be found here:
Link