Many first responders are well aware of the fact that if they encounter a Subaru vehicle in a MVA, there will be UHSS or Boron to deal with. Here is so information that Subaru made available on their website.
The A-Pillars and B-Pillars in the Subaru Forester are reinforced with Ultra-High Strength Steels. For example, notice the orange colored rod in the image of the B-pillars on the left? That short reinforcement rod mounted along the mid section of the B-pillar is Boron. The reinforcement that is colored blue is a steel plate made from UHSS. Both are in the same location on the B-Pillar. These Notice the solid steel rod in the A-Pillar section on the right? That is a Boron reinforcement what Ron Moore calls a “rod that resembled a concrete reinforcement bar (rebar)”.
Subaru uses what is called a Ring-Shaped Reinforcement Frame. The structural body pieces form three rings the connect around the sides, top, and bottom of the vehicle. Below is an image of the Subaru Forester. The green body structure members are what makes up the Ring-Shaped Reinforcement. The three Ring-Shaped reinforcement sections include the A-, B- and C-pillars.