We make our BMW engine mounts out of 3 different materials - polyurethane, UHMW, or solid aluminum. Each material is designed to perform a specific function. The easiest way to explain the differences between the materials is not by hardness but by function. What are they designed to be used for?
Street - 70A Polyurethane - This is our VIP collection, an OEM+ upgrade designed for minimal vibration. These mounts are only 30% stiffer than the stock mounts, so they're perfect on a street car.
Street/Track - 68D UHMW - This is our Classic collection CNC machined from a hard plastic much stiffer than stock. These mounts were originally designed for racing, but we've found that they perform well on the street when vibration is not a major concern. As engine mounts, in e30 applications they hardly transmit any NVH, but in E36 & E46 applications you will feel some vibration at idle and lower RPMs. UHMW is the perfect material for
Extreme Track - Solid Aluminum - This is our battle ready Armageddon collection designed to take all the abuse you throw at it. Vibration should be expected.