The last 25 years have seen some improvements, but nothing nearly as dramatic as the change between the 25 years prior to that. Seatbelts, airbags, crash testing and designing a car for survivability in case of an accident are all things that happened between 1970 and 1990, since then we've seen incremental improvements but for the most part things have not changed all that much. That's also why automobile manufacturers have trouble introducing new models because the older ones are really pretty good. The car I'm driving has gone through 2 upgrades since 1997 (the year it was built) and neither of those is a huge improvement safety wise over the one that I've got. The biggest question mark is probably the longevity of the pyrotechnics and the airbag materials, but for both I've been reassured multiple times by the dealership that they are fine (not something you want to test), and that this goes for any airbags manufactured after 1993 except for one particular notorious bad batch made by Takata, and those fortunately are not in my car.