What device is added to cars to improve stability when cornering?

The stabilizer bar, also known as an anti-roll bar, plays a crucial role in enhancing a vehicle's stability during cornering. Its primary function is to reduce body roll, which occurs when a vehicle turns and the center of gravity shifts away from the direction of the turn. By connecting the left and right sides of the suspension, the stabilizer bar distributes the lateral forces experienced during a turn, helping to keep the vehicle more level and stable. This reduction in body roll allows for better tire contact with the road, improving handling and safety.

While suspension struts, anti-lock brakes, and lowering springs are important components of a vehicle's overall performance, they do not directly address the specific issue of body roll during cornering. Suspension struts support the weight of the vehicle and absorb shocks, but they do not inherently stabilize the vehicle in a turn. Anti-lock brakes prevent wheel lock-up during hard braking, enhancing control during stops instead of in turns. Lowering springs simply lower the vehicle's center of gravity, which may have some effect on handling but does not provide the same stabilizing effect that a stabilizer bar offers. Therefore, the stabilizer bar is the most effective component listed for improving a car's stability when cornering.