Shooting from inside a car??? Ouch! I went to the range a few years back to sight in my mini-14. It was raining, wet and muddy, and I forgot my ground cloth. Now I have a pick-up with a cap, so I set up from the bed of my truck. Never thought to open the windows in the cap, but I did put on extra ear protection. Wasn't enough. The concussion felt like Mike Tyson had hit me from all directions at once, and my ears rang into the next day. Trust me, I won't do THAT ever again!
I had the same thing happen to me about a year ago. You described it perfectly. I was at a small indoor gun range...like your case it was raining and nobody else wanted to come out and shoot. I was there alone. My eye protection kept fogging up, no matter what I'd do. I kept taking them off (along with my ear protection to get them back on) and wiping them or spiting on them. I forgot to put my ear protectors backon and picked up my OP .38 and BAM!!!! RIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIG
(From then until the next day)
It was VERY distracting and made me tired as you couldn't close the ringing out.
IC people in movies do things like that all the time. Firing off their guns in closed in areas with no seeming effect on their ears. (A scene in Dirty Harry: Magnum Force comes to mind when one of the crooked biker cops is chasing Harry through the closed in metal corridors of a ship rapid firing off all 6 of his Python .357 rounds at Harry. No problem, he just reloads and does it again)