A system and method using a mount assembly for attaching a powertrain to a structural member of a vehicle. The mount assembly includes a first compliant member, a second compliant member, a first fluid chamber, a second fluid chamber, a pressure compliant membrane, electro-magnetorheological switch and a magnetorheological fluid. A fluid conduit interconnects the first fluid chamber with the second fluid chamber to allow a fluid to pass from the first fluid chamber to the second fluid chamber. The pressure compliant membrane seals the aperture in the second fluid chamber. The electro-magnetorheological switch is activated to generate an electric field in the fluid conduit to change the viscosity of the magnetorheological fluid to achieve a first stiffness profile of the mount assembly. The electro-magnetorheological switch is deactivated to remove the electric field in the fluid conduit to change the viscosity of the magnetorheological fluid to achieve a second stiffness profile of the mount assembly.