SUMMARY The paper is concerned with the possible performance improvements which can be obtained in an automotive active suspension system through the use of adaptive rather than fixed control. The study is wholly theoretical and treats a quarter-car, slow-active, electro-hydraulic-pneumatic suspension with elastic limit stops, through simulation of running at a constant speed on randomly profiled roads. The adaptation is intended to adjust the system operation according to the prevailing road roughness level. mad spectral properties being assumed average at all times. The road roughness estimation process is illustrated. The estimate is used to drive a gain scheduling adaptive scheme. Comparisons are made between adaptive slow-active systems. non-adaptive slow-active systems and a typical passive system. mainly by means of root mean square values of response variables. It is concluded that the assumptions made in such a study can exert a large influence on the nature of results obtained, giving rise to po...