|The primary purpose of the rear subframe bushings on the Z32 is to isolate the passenger compartment from the frequency spectrum generated by the driveline, specifically the rear differential geartrain and the rear portion of the driveshaft.
Being that a civic is a front wheel drive car, the rear subframe does not house any drivetrain components and therefore can be hard mounted to the chassis. Road frequency inputs are damped out by the control arm and damper mount bushings. Note also that the front subframe of the Z32 is also hard mounted to the chassis for the same reason.
In the civic, the drivetrain noise is isolated from the chassis by having rubberized engine and transmission mounts.