THE heart of any Peugeot is its suspension system and the 406 is a perfect example of the company's art. The system comprises "pseudo" inverted MacPherson struts at the front with lower wishbones and a de-coupled anti-roll bar and, at the rear, a fully independent multi-link layout with transverse and longitudinal links to compensate for cornering loads, acceleration, braking and surface irregularities. The secret of how it all works is in the careful location of linkages and choice of spring and shock absorber rates - a formula that still eludes many suspension designers. The rear suspension's transverse and longitudinal links compensate for cornering loads, acceleration, braking and surface irregularities. The rear suspension incorporates passive steering to enhance stability and steering accuracy, and is designed to progressively toe-in under load.