If you were to change the rear engine mounts, might as well change all of em.... then again the car being only less the 5 YO, the mounts should still be in good condition. if your car have no vibration in idle, cant really feel the engine, I dont see the point to change the mounts. I dont feel any vibration in my 06 CL9, so I dont see why your 08 built need to change mounts, my mileage is around 60+k, slightly less then yours.
