the s4-e incorporated the technically advanced features of the s4 da such as an engine with twin overhead camshaft, hemispherical piston heads with the centrally positioned spark plugs. the chassis featured rack and pinion steering, with independent suspension at the front. however, the front suspension was now refined through the addition of longitudinal torsion bars, an approach probably copied from the citroën traction that had appeared the year before. commentators noted that the new engine and suspension enhancements gave rise to a combination of performance and road-holding that was among the best in class for the time. another novelty for the s4-e was a hydraulically controlled brake circuit in place of the then conventional mechanical linkage.