I will try to be more specific with my phrasing, but my original reply agrees with your thoughts. Most cars are only designed to do well in current tests and only have a little extra headroom for updated tests. In the case of the updated side impact test, only the Mazda 3 retained a good rating, while the Civic, Sentra, and Corolla all dropped one level to Acceptable. In the case of new tests, such as when the IIHS first introduced the small overlap test, only a few vehicles that were designed for the scenario performed well.