Abstract: A vehicle level controller produces a level lowering command signal whenever the sprung mass of a road vehicle is higher than a given trim band and produces a level raising command signal when the sprung mass is below the trim band. The command signal is applied to a levelling system. The trim band is divided into a high (medium high) and low (medium low) regions. A vehicle level detector produces a signal which distinguishes a vehicle level in four different zones including a range higher than the trim band, a medium high region within the trim band, a medium low region within the trim band and a range lower than the trim band. The level lowering and the level raising command signal are withdrawn whenever a signal from the level detector indicates the medium low and high region within the trim band, respectively.