An article clearing it up a bit:
https://www.autocar.co.uk/car-news/new-cars/renault-zoe-give...Matthew Avery, Euro NCAP board member and chief research and strategy officer at Thatcham, told Autocar: “Every few years, Euro NCAP raises the bar by introducing new tests which either exploit new technologies or lift the hurdle to make manufacturers do better. If everyone is five-star, we need to lift the barrier."
As a result of these alterations, he explained: “When we first tested the Zoe, it did reasonably well and had all the elements you needed back then to get a reasonable score. But if you've still got the same design 10 years later, you aren't going to score as well.”
"The Zoe was launched in 2013 and received 5 stars with Euro NCAP protocol at that time. The Euro NCAP protocol has since 2013 undergone five changes. With the same equipment, a model can lose up to two stars in each protocol change.
I was not aware how quickly and dramatically the tests change, it makes comparison between different models almost useless unless you read through entire test protocols.
Matthew Avery, Euro NCAP board member and chief research and strategy officer at Thatcham, told Autocar: “Every few years, Euro NCAP raises the bar by introducing new tests which either exploit new technologies or lift the hurdle to make manufacturers do better. If everyone is five-star, we need to lift the barrier."
As a result of these alterations, he explained: “When we first tested the Zoe, it did reasonably well and had all the elements you needed back then to get a reasonable score. But if you've still got the same design 10 years later, you aren't going to score as well.”
"The Zoe was launched in 2013 and received 5 stars with Euro NCAP protocol at that time. The Euro NCAP protocol has since 2013 undergone five changes. With the same equipment, a model can lose up to two stars in each protocol change.
I was not aware how quickly and dramatically the tests change, it makes comparison between different models almost useless unless you read through entire test protocols.