The benchmark problem, “Design and optimisation of restricted complexity controllers”, for an active suspension system is studied. An initial fractional controller based on the first and third generation Crone methodologies is designed first. The high-level parameters of the rational controller are then fine-tuned using a tuned in closed-loop approach. The optimisation technique uses the power spectral density of the closedloop simulation of the residual force to be minimised. This final controller is finally assessed with real-time implementation.