Originally Posted by 
ADMIRAL
				 
			There are different 'duro' ( hardness ) ratings for the urethane bushes as distinct from poly bushes.  The urethane bushes are cheaper to produce in small batches than rubber ( and it is safe to assume the same applies to  poly bushes )  This makes it cheaper to manufacturer a product in smaller runs, where rubber would be uneconomical to produce a copy.  If the volume used is up, someone probably has a rubber copy. ( but the OE rubber bush is still probably a better bet ) 
So Poly & Urethane are cheaper to manufacture than rubber.  Answer this question.  Which automotive manufacturer uses Poly or Urethane bushes as std fitment ? If it is cheaper to make and has such great properties, why aren't they using it ?  .......and remember auto manufacturers are chasing cent savings per vehicle, and this stuff is $'s cheaper !!