Prepper Stash: Getaway
Find this stash at McCallough's Garage in Faith's Region.
Scan the place before getting too close. In particular, look for shooters and a gun emplacement on the roof.
When you've cleared away the hostiles, find the prepper note inside, by the cash register on the small table.
Enter the garage from the back (south), by busting through a barricaded door there.
Hit the button at the end of this narrow passage to open the large garage door. A car will roll out into the driveway.
Go around to the front and enter the garage. Bear left, and go through the office door.
Go left here, hop up on the boxes in the corner, and turn right.
Drop down to the floor, and crouch through the passage south, but be ready for a wolverine attack.
Turn left into the restroom, and grab the keycard from the wall.
Open the locked doors by the prepper note and step inside the stash to complete the mission.
You'll also unlock the 1973 Pygmalion SSR for use.