Sorry for the long post guys Im taking over temporarily from Jmac's absence! ;)
There is always going to be debate between Industrial designers vs Engineers but to put it simply all car designs borrow from each other as does art.
We can discuss that so many cars look like such and such and even the design team responsible were given themes by the market research departments that were not usually followed or impossible to.
As for total rip off yes but not the mustang, that was done already as mentioned for the kb10, the new 1200 was a borrowed idea from Hillman out of all places but on the new successful Dodge offerings that targeted the mustang.
In Oz and Japan as well as many other countries that were economically just behind USA, the kb10 mini early mustang look was a success for those that couldnt afford the real deal. The auto journalists had a field day with harsh words for it and the Z that the Jps could not come up with anything original themselves but to copy the western world.
You have to understand that although the Merican market was a successful target by Nissan, the pro Detroit biased auto journalist said most jp cars were blatant inferior copies of great world cars. They were so they had to up their game.
The main interest of the Japanese designers for the local market was using Italian cues specifically Carlo Abarth finishes or Abarth like souping up. Carlo Abarth was a reason the rest of Europe and latin Americas did what we do to datsuns but to fiats but earlier. Budget nimble lightweights into hobby pocket rockets.
I was fortunate to met one of the original Nissan stylist department workers in Kyoto in 1997 in a Nissan club outing and from what I understood and didnt at the time was those examples mentioned were the main themes.
The kb10 even had giveaway chopped down tailights from the early mustang. Therefore dogs breakfast main ingredients mentioned (Fiat, Chevy & Dodge) were the new thems for new 1200 as it had to move away from the mustang kb10 effort
which was a bit embarrassing for the stigma of westerners saying jp just copy.
The fairlady Z era datsuns were more obvious but the Nissan made a stronger effort in the latter part of 1969 to be less give away to what the auto journalist were saying hence the more original looking design cues that even borrowed from other Japanese cars but using single headlights and further
cutting down of usually obvious giveways.
Nissan acquired the Prince company and the Jp Gov pushed its makers to style
their cars with originality but it was easier said than done.
Again going to go further into design here so sorry for the long if boring post :(
Japan retro is a massively influence by USA since it is afterall USAs biatch.
It was not only Nissan but other Jp makers that started by using Italian styling companies to help with their products and even these hired foreigners used Merican styling as they themselves could not help be influenced by this strong force.
The Italians had no choice as many of their own countrymen where part of the Grand plan / scheme to create the whole new image for USA that would help its consumer products dominate world wide. Therefore with the help of the CIA (this info is even in your local library) snatched or enticed many famous designers from around the globe, post and during the WW2 to make the USA retro movement.
USA hired Europeans engineers, designers and artists from all over the world to even move the capital of art from Paris to New York and entrench the retro movement throughout all of USA products after the WW2.
Japan looked at Italian and Detroit style products and borrowed heavily in the 60s but by 1970 they formed their own detroit simplified retro DNA. Mazda was the more successful in making the most unique jp car designs ever seen but Nissans choice of simple is best is also a reason why the 1200 is so sought after because there is nothing like it.
Its a coke bottle design made in Japan but not dissimilar to its over the pond theme that is subconsciously in our taste buds for halve a century since its introduction and the reason many go for the fanta ink for the 1200s.



Hillman on the other hand failed at the B Car proposal while
Nissan took it and ran with the Avenger proposals and made them
their own for the 1200 and 120y using r429 concepts.
yet the main theme was the Dodge challenger barracuda lines
Avenger R429 Coupé eg.
http://www.rootes-chrysler.co.uk/hill-ave.htmlFlatto would be interesting for your input to see what they taught in your
modern background of industrial design compared to mine. Its all fascinating.
another Dodge effort by Morris pay attention to that front end!
Austin, Morris, Datsun which came first the chicken or the egg :)
https://www.youtube.com/watch?v=MwGDzaUqa0s