The prerunner configs don't have those door types used. But the Rock Runner and the Superpig do use them. i'm blind
They have been in the parts menu of the Hopper for months but not used for any Hopper configs so I guess they ported them to the D-Series
This probably means we are getting a 2 liter inline 6, since BMW did not use 2 liter inline 4s in the 80s. All 320s until the E90 have a six-cylinder, except early E21s, all 520s until the E60 have a six-cylinder except early E12s.
Like AgentY said, those doors have been in game for awhile. IIRC The Hopper got them when the crawler was released and this past update ported them to the D-Series. Just an alternative personalization option, not every part needs to be used in a config. As for badges, I wouldn't think too much into them. There's a fair number of unused badges in the files, including a Kentarch D20 and some modern ETK stuff. Some of it might be just for player use, some stuff in dev limbo/abandoned, some stuff planned for later use... I'm sure each has a different story as to why it's in game.
Here are the modern ETK letterings, I assume the 5 means 5 doors, so it is probably for a sedan. For the K, there are 8, 10 and 12 lettering, so we might be getting a V8, V10 and a V12...
This is very old news. Those textures have been in game since the cars were added to the game. Honestly i hope that at some point the 800 and the K-Series gets revamped. Specially the K that seems rather... abandoned.
Frankly, I think a 2-liter inline 5 would fit well, since it would pretty much be the existing 2.4L I6 with a cylinder chopped off. Give the car something a little unique but not entirely out-of-the-question.
The I 2000 might be a little closer than the 844/846 and Kc8/Kc10/Kc12 to being finished since the badges are already in the game.