Black steel strut brace for BMW 5 Series E60/E61 — TA Technix

The bar connects the two shock absorber mounts. In a hard corner, the loaded suspension assembly pushes outward and the geometry deteriorates at precisely the moment you need it 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 noticeable on older chassis, convertibles and high-mileage cars; it is more subtle on a modern body that is already rigid.