I guess if they imply that 'classic' should be 'rare, desierable and collectable' then the GNX fits the bill. However, if they only made 547 of them it does not give the rest of us much opportunity to enjoy them.
(Although I am sure there are a lot more than 547 GNX's now, if you know what I mean)
I think they should include all Grand Nationals as being classics too.