Sorry, I am too recent of an addition to the forum. Don't even know what "ACCA" stands for. 
But I did some reading in past posts and I think I know where you are coming from.
My Prov is when you deal with older, collectable vehicles, it depends very much on the specific model whether a certain term to describe it, applies.
I usually differentiate between "Classic" and "Vintage".
A "Classic" is no longer produced, was -maybe - produced in low numbers and due to its rarity and value it has become somewhat desirable among collectors, hobbyists and enthusiasts.
A "Vintage" is mainly of a certain age regardless of actual numbers originally made or still out there. This may not necessarily be a desirable vehicle for most.
I am not including American made cars in this, as that market is totally screwed up and there are too many fakes and plastic repops out there. Personally, except for the occasional Corvette, I stay away from them as you cannot possibly be an expert in everything that is out there.
So, the terms "Classic" and "Vintage" can be applicable simultaneously to a specific vehicle model, or they can divide a model range over the time it was produced.
The perfect example is the cooled Porsche 911. All are most certainly "Classics" while "Vintage" I would only accept for the pare-964 models.
And to make it more annoying, some people in the "scene" even use the term "Neoclassic".... 
A lot of people believe these things and just because people believe things doesn't mean they're true.
Before the second world war, there were basically two types of cars produced. Antique cars and Full Classic Cars. Built during the classic era of car building these were mostly hand built high dollar cars. Think Auburn, Cord, Duesenburg, Pierce, Peerless, Packard, Marmon, V12 Cadillac, and large number of European high end cars. MB S, SK, SSK, 540K, 500K and a few others come to mind. There is no way someone could mistake a Full Classic for an antique car like a model T or model A. It's all about the era in which they were built and how they were made.
After the war, the ACCA ( Antique and Classic Car of America ) formed in 1952 to save what was left of these cars - long before a 1968 Corvette was ever built. In response to the growing number of post war car clubs and car enthusiasts, a new club was formed called the Milestone Car Club of America. This covered everything from 1947 until 1972. A number of MB cars were recognized such as 220 Cab A, 220SE Cab and Coupe, 220 S Coupe and Cab, all 300 cars, 6.3, 600, 190SL, 111 coupes and cabs, and 113's.
I don't know if this club is even active or still around but the bar was set a long time ago as far as what's in and what isn't. The ACCA is still active and every year new cars are voted on and added to the list. This is not my idea of how things should be, it's the way it really is.
The whole idea of "Classic" is so bastardized anymore that anything older than a toddler would qualify. It's almost meaningless these days. One day, during a discussion I was in ( imagine that ) a guy asked me if I had ever heard of Classic Rock. I said yes, and it's not the same as Classical music - those are two very distinct and different things. I think of Full Classics and Milestone Cars in the same way. Everything else is just old cars and used newer cars.
