The main thing that caused car styles to get so similar is that people tend to buy what's stylish. Or at least that's what car makers think, i'm not totally convinced. When something different is built, it's usually either the car that everyone loves but nobody buys or is treated like the biggest piece of crud either, then becomes a cult classic.
Back when the automobile first started, for example, they all looked like horse carriages. Why? Because a lot of the early carmarkers were carriage-makers as well, and hence why a lot of car terminology comes from the era of horse carriages.
Have you seen how many different types of carriages were made? There was far more variety of body styles in up till about WW1 than there was afterward.
We have seen a few new car tipes the last few years. The SUV, very compact cars like the SMART, those company cars built on a small car chassi with two seats and a fairly big baggage compartment, higher then a small car. (What do they call them anyway?)
I suppose those could have evolved earlier.
Very compact cars? Like, say, the
Isetta? Cars like that were very popular post-WW2, and declined very quickly when people could afford something bigger.
Let's see, SUV, like this? 1948 CJ2 Overlander.