Body roll in a car refers to the axial rotation of the vehicles body towards the outside of a turn. It occurs because the compliance in the vehicles suspension allows the vehicle body, which sits upon the suspension, to lean in the direction of the perceived centrifugal force acting upon the vehicle. Body roll is a function of a cars suspension system, and each manufacturer builds an element of body roll into their vehicles that most closely matches the driving characteristics they desire.

Body roll can be uncomfortable for passengers and cause damage to cargo. It can also allow a vehicles center of mass to move towards the outside of the turn, increasing the load transfer to the outside wheels, which can cause understeer or oversteer to occur more easily than if body roll was not a factor.

Anti-roll bars are suspension components designed to mitigate body roll. They do this by connecting the wheels at either end of an axle with a torsion bar attached to the vehicle body. Body roll can also be reduced by lowering the center of mass of the vehicle body, fitting stiffer suspension springs, and reducing the sprung mass of the vehicle.

In summary, body roll is the weight transfer that occurs as a vehicle turns to one side or the other, and it is a function of a cars suspension system. It can be mitigated by anti-roll bars, lowering the center of mass of the vehicle body, fitting stiffer suspension springs, and reducing the sprung mass of the vehicle.