A car's safety rating comes from a specific programme, in a specific region, for a specific version — so the first thing to check is not the number of stars, but who tested it and where.
The programmes don't share a scale
There is no single global safety score. The United States has two independent programmes: NHTSA gives stars (1 to 5) per crash type — frontal, side and rollover — while the IIHS gives a word — Good, Acceptable, Marginal or Poor — for each of its tests, plus its Top Safety Pick award.
Europe's Euro NCAP gives an overall star rating and a percentage for each pillar (adult occupant, child occupant, vulnerable road users, safety assist). Latin NCAP (Latin America), ANCAP (Australia/New Zealand) and ASEAN NCAP (Southeast Asia) work the same way, each with its own pillars.
Because the scales differ, a five-star NHTSA result and a five-star Euro NCAP result are not the same measurement. Compare a car to others tested by the same programme, never across programmes.
A rating from another region may not apply
The same model built in Brazil, Mexico or India can carry fewer airbags and a different structure than the one sold in the US or Europe. A regional programme tests the version sold in its region — that is why MotorHangar labels every rating with its origin and, when it comes from another region, warns that it may not apply to the car in front of you.
It is still worth showing: a crash-test result from another market is real data, and often the only data a given model has. Read it as a strong hint, then confirm the exact version and airbag count with the seller.
Ratings expire
Euro NCAP tightens its protocol every few years, so five stars from 2017 are not five stars today. Always read the test year next to the rating — an old five-star car may score lower under the current test.