NYS DMV considers 25 years an antigue, very subjective of course, just as what is a classic, lots of different opinions on the " classic" issue, what car are you referring to.
The car I had in mind is a 91' Cougar LS 3.8 its located at the following link. The car had 32,000 when i got it a year ago and has never slept outside in the elements.
When I think of an antique car, a Model T comes to mind. A classic car would seem to fall as far back as the '50s. A Model A Ford or a Duesenburg doesn't seem old enough for an antique status but looks too old to be a classic. It's a tough call and I can see where it too depends on the vehicle. I'm sure it's written in stone somewhere on times and conditions.
Pre-war and post-war comes to mind. I'm just not exactly sure what it applied to. Maybe it was a classification for tractors or something.