to run such hydraulics, look up the mercedes self levelling suspensions that were used in the older W123/w124 etc station wagon rear or the W140 and all ahead S classes on all 4 wheels.
basically the system runs like a citroen DS system, an engine driven hydraulic pump supplies oil to the hydraulic lifting rams on each wheel where the shock absorber would be - this is regulated by the height control valve assembly placed on the chassis and levered by a suspension articulation piece.
The shock absorption is done via partial nitrogen parital fluid filled diapghram chambers otherwise the lifting rams will act like steel rods. The diaphragm chambers can provide a buffer and expansion chamber for this purpose. In engine off condition the entire car rests on the residual pressure locked in from the level valve and springs (in old models)
To make it work in a Honda City you will be spending close to Rs 500,000/- to incorporate this design into the car, it would require major cutting and a truckload of work to get running. Not to mention getting someone to actually tackle it and the same someone to repair it when the need arises.
A little example of this is that - some toyota crown models came with this system - ALL of those cars in Karachi atleast had those systems removed and basic springs and shocks installed because of the stupendous repair costs involved.