In a nutshell, even in the mass-market car class, it was becoming an era in which luxury on par with advanced cars was required. The design, which is reminiscent of the Kenmeri Skyline and Bluebird U, is surely the answer

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The oil crisis and the emission regulations that followed greatly changed the shape required for mass-market cars, but I think it was difficult to foresee this at the time of the development of the 210.[/url]

thinking on this, and the american market I grew up in, i see the similarities. At the time, US cars got more ornate/luxurious -- although the cars were always one size bigger than JDM (we didn't have the smallest class, and they didn't have the largest class). Yet at the same time (1973) the oil embargo hit, ultimately resulting in accelerated down-sizing. I wonder how Japan reacted? He mentions it "changed the shape" of cars