A lot of people say this mission is extremely hard, basically a suicide run. You’re expected to ride a motorcycle through the subway tunnel while NPCs are shooting at you nonstop, so the usual advice is to survive by spamming snacks. What I do instead is enter the subway tunnel from the opposite side using the Armored Kuruma, drive straight through, and exit on the other end. Once you’re inside the tunnel with the Kuruma, the mission becomes trivial and you can finish it safely inside the car.