I think the main “gap” might be the late 50s, when the cars started looking more and more like proper sedans, but before they adopted the boxier style of the 60s landbarge we have.
We currently have Kubby’s Cadillac as well as the other fairly large sedan that was added recently that IMHO fit fairly well for the american styling of the early 50s and late 40s, with the upscaled Moris Minor also fitting decently well for the stuff from right after the war.
A car I think might be a good addition would be something like the 55 belair, with the ability to morph the headlights to fit two round headlights side by side, which was fairly common a few years later.
It’s a very recognizable shape, and probably the easiest body of that era to create something that looks decently generic, since later models from the big 3 started having more and more complex front and rear ends.
Edit: I also agree with @Awildgermanappears for the 49 ford, an other very recognizable amd simple shape that’s also represent it’s era very well.