In the RS 4 suspension, a fluid hydraulic linkage between diagonally opposing front and rear suspension dampers (left front to right rear, and vice versa) is used to counteract vehicle pitch and roll. Lightweight magnesium/aluminium alloy multi-link suspension arms (four arm with virtual steering axis up front, and trapezoidal arm with unequal length track control arms at the rear) locate each hub/brake/roadwheel assembly in a controllable fashion, whilst minimising unsprung masses. Lightweight hollow tubular anti-roll bars are standard front and rear. Compared to standard B7 A4 models, the RS 4 features a lower ride height. An optional "Sports Suspension Plus" lowers the car by a further , and marginally further stiffens the damper rates.