The cars of today are much more constrained in terms of aerodynamics (fuel economy) and safety than the cars of yesteryear. There were cars in the 50s that had better aerodynamics backwards than forwards, and just watch one of those videos of an old car in a crash test collapse on itself before they figured out safety cages. There are essentially a very few optimal designs for safety and economy, so these days everything is essentially tweaks off that.

Maybe we can have fun designs like this if there are ever city cars with low speed focus and regulations. I can only imagine how much fuel those cars in your link would use at 70 mph (if they ever got up to that speed)

Engine technology has improved substantially, so I don't think you need to adopt 1960s horsepower in order to get 1960s quality body design. Aerodynamics takes a hit, so maybe that powerful engine wont hit 140mph, but it will have plenty of power and acceleration with a modern engine. And even for non-boxy cars, look at some of these streamline designs: https://1u4we0207ruc34o1s412c2ca-wpengine.netdna-ssl.com/wp-...

Cars these days are shaped more by a wind tunnel than a designer. This is especially true for EVs where range is an important number.