does the subframe bushing get damaged from jacking
 

When i jack a car on the frame I notice that the subframe bushing gets stressed/seperated. It seems that the entire weight of the wheel, axle and associated suspension is being carried by the rubber. Can this damage the subframe bushing? Jacking the control arm instead of the frame does not stress the bushing.

This is the normal jacking point for your car. Actually the jack holes that Mercedes installs. But whether you do the frame or the jack holes, you will produce the same affect on the subframe bushings. If they are "seperating" while jacking then I would believe the subframe bushings need replacing. It is a rather stout rubber unit that is designed to take the loads your puting on it. If it is separating then it is worn out. The front rubber on the car gets mushy and soft as it ages, then it usually collapses as it compresses, this is caused by the heat and fluids that get on it in the engine compartment. I have seen the subframe mounts just drying out and cracking.

Dave