Circuit de Catalunya
When the circuit opened, overtaking was frequent. Cars could closely follow each other through the last two corners. They would slipstream down the long straight for a pass. As aerodynamic balance became more important, this overtaking method became less effective. The cars were unable to follow each other as close. They would encounter turbulence created by the leading car. This made it hard for a car to get close enough to pass. In  the next to the last corner was replaced with a chicane. This was an effort to improve passing. The redesign did not increase the amount of overtaking.