I've just been curious and tried to recreate it on local, and there it was:

First I took the jeep for a joyride to docks and back, getting in and out of it several times, but nothing happened. I had a crewman kit this time.
I went back to main, tried the new RPG 26 optics a little and went off with the jeep again, keeping the LAT kit.
This time I made a short stop at the promenade, et voila, the windshield went black when I was outside the vehicle. I made the screenshots and ran away a hundred meters, came back but the windshield was still black.
€dit: I didn't change serverfiles or something, I capped the first flag regularly for the jeep to spawn.