Here's an evil thought I had on another thread, what might a German Covenanter equivalent look like? That is too say a tank that 'looks the part', is reasonably capable on paper, but has the same hideous radiator issues as the British tank did and yet gets built in numbers such that the Wehrmacht has no choice but to deploy it. Like I say, an evil thought.
One possibility comes to mind: these handsome fellows.
The charmingly named Neubaufahrzeug, literally translated as "new construction vehicle", could be right up your alley. Descending from a couple of different cracks at an earlier design called the Grosstraktor (which itself is an obscure piece of tanklore, but you can read up on it
here), the Neubaufahrzeug actually had (seemingly) enough momentum behind it as a project that it was briefly considered (not by Germany, mind) as being the actual Panzer V by Soviet intelligence (note that this was after the actual Panzer IV was developed - the Panzer "V" in this case predates the IV by three years or so; military intelligence is funny that way, as it isn't like they have the exact timetable of what came when, especially as Germany was trying to be sneaky with the thing and took photographs from different angles, etc). Five units were built, as well as two testbeds out of mild steel, and they ultimately ended up being little more than a propaganda piece, and the only one that ever went into battle was shot up by anti-tank rifle fire and lost a crewman. But if you ignore the benefit of hindsight, the "Panzer V" has some selling points to consider; it has guns for days in a good three turrets, including the same 7.5cm KwK 37 that we'd see on the early Panzer IV
and the same 3.7cm that went on the Panzer III
and three machine guns, including one in a rear mounted turret, whilst also seemingly (if Wikipedia is right) having the same on road speed as the Panzer IV of the day, so it isn't likely to get rejected for being too slow. Without the various lessons as to why multi-turreted landships probably aren't the best idea, the thing looks pretty sound by specifications alone. There's also the fact that the USSR is just over there, with the T-35 and T-28, which are fairly similar multi-turreted designs, and perhaps some element of "keeping up with the Jones" could be described to be in play if you wanted to use it in ATL; the Soviets have built them, so maybe some German officer goes "y'know what, they might be onto something with this" and pushes for the project. Else, you could say that a designer managed to get a sneak peek at the then state of the art T-28 before the Kama tank school closed, or something along those lines which you can use for in a story/timeline. There may be some exaggeration in this for comedic effect
But as Wikipedia helpfully describes, the thing has...problems.
The Neubaufahrzeug was intended to fulfill the role of a medium tank in Germany's developing armored force, but it proved to have too many problems with its front drive and aero-engine for this role.
This propaganda role was extended with the German invasion of Norway, when Panzer Abteilung z.b.V. 40 (40th Special-Purpose Tank Battalion) was formed for supporting the invasion of Norway, and the three Neubaufahrzeuge were assigned to that unit. One vehicle was assigned to Kampfgruppe Fischer advancing north through the Østerdalen Valley, while the other two were assigned to Kampfgruppe Pellengahr advancing up the Gudbrand Valley. The one assigned to Kampfgruppe Fischer was immobilized with mechanical problems on its way to Lillehammer, while one of the two assigned to Kampfgruppe Pellengahr also had mechanical problems just north of Lillehammer. Only one tank actually made it to the front; it was immediately put in action with the German force advancing up the Gudbrand Valley with other elements of Panzer Abteilung z.b.V. 40.
If you wanted to be cruel with your evil idea, you could have the Neubaufahrzeug actually do a little better in its testing stage with reliability, leading to it actually getting accepted for mass production as the Panzer IV, pushed into an infantry support niche. A few hundred units later, refinement of the concept of a medium tank eventually leads to something similar to the historical Panzer IV as the new Panzer V, which has the advantages of being mechanically simpler to build and maintain due to having just one turret, making it easier to put together; useful for a country in the midst of building up for war. The older Panzer IVs/NBFZs are kept, as a tank is still a tank and Germany isn't exactly in a position to be picky, and when war comes, they're sent forth in their role as infantry support...
...only for their reliability issues to rear their ugly head once more, with issues with engines and front drive, all the bonus complexity that comes with a tank with three turrets, then the issue of being nearly ten foot tall and wide, twenty feet long, with a crew of six men in a metal box with 20mm of front armor and much less on the sides.
Does that qualify for being a bad enough tank, or is it outside the realm of possibility for mass production for you?
If they did have enough
lead paint chips determination to make a large number of them, I'd actually expect the hulls to find some new usage before long (the base hull is nearly the size of the one on the Tiger II, but weighs a third of the weight), or at the very least a drastic redesign of this new Panzer IV. They won't keep it in this awful state for long, but I could imagine them ripping out the secondary turrets and slapping on more armor to try and make it into a more versatile medium. Alternatively, due to the size, they could just take an axe to the whole upper structure, taking all three turrets out, and then use the hull to make a monster of a casemate, perhaps some sort of self propelled howitzer. It might not be perfect, but it could be a useful foundation for something.