The bar connects the two shock absorber mounts. In hard cornering, the loaded suspension strut pushes outward and the geometry deteriorates precisely when it is needed most: the bar distributes the load between both sides.

The front end responds more directly when turning in, and the car maintains the same response from one corner to the next. The effect is clear on older chassis, convertibles, and high-mileage cars; it is more subtle on an already rigid modern body.