Were WW2 tanks as maneuverable as shown in Girls Und Panzer?

So anyone who frequents the Garupan subreddit knows that I'm a rabid Garupan fan, and I've done a fair bit of looking into this. I'm no expert on armored warfare (barring an awful lot of reading I did as a kid), but we do have one flaired, so mebbe he'll show up. Hell, I'm not even a military historian. So I can't answer all of your questions, but I think I can help out.

Tanks drift Tokyo-style through tight turns

That actually happens. Here's one that's not Russians. Here's my favorite one, on dirt rather than concrete (as I understand it the Russian army trains this maneuver, but don't quote me on that). I had this whole thing explained to me by a guy who used to actually help design tanks, but I'm no good at physics so it was all totally over my head. From what little I understood the weight of the tank distributed over the surface area of the tracks allows sudden changes in direction like that (which, incidentally, confused a lot of people who play War Thunder). Now, are they able to do it as rapidly as many of the tanks in Garupan? No, not really, except in the case of the video of the tank doing a 180 on dirt. The other videos I linked were all on concrete, and that was for a reason--notice how the movement was much more restricted? Particularly the Chinese one--at slow speed on concrete not much drifting is possible. Even in Garupan, not only do Anglerfish Team's tracks snap, but their roadwheels are even ripped off, because of how fast they're going!

Tanks get into one-one-one duels. In one duel they circle each other trying to get a shot at the other's flank. In another duel the tanks are bumper to bumper trying to stay too close to be shot and sometimes resort to 'sword-fighting' with their barrels to disrupt each other's aim.

The duel between Carpaccio and Caesar in the OVA has a single analog that I'm aware of. In particular the jousting bit is similar to this incident during the Korean War (go to page 17). HOWEVER, I'm more than a bit skeptical of the source, but it's at least documented, though they don't cite where they're getting it from (presumably the after action report?).

/r/AskHistorians Thread