Argonaut said:
Classic cars are those that have had some major impact on the motoring world - stuff like E-Type Jags. Old cars are just that - old. They haven't had the impact the others have had - would you call a Citroen 2CV a classic?
Actually, the 2CV pioneered much of the French car industry as we know it. Initially it wasn't as sensational as intended, but the 2CV has since become a classic. There are many fan sites out there, clubs etc that feature the 2CV in race format, rally format, original format, etc. Something like 5 million 2CVs were built up until it was discontinued in the late eighties, to the dissapointment of many. So yes, I would call the Citroen 2CV a classic, not for its nostalgic value but its value as a pioneer - in the same category as the Beetle, the Model T Ford, FJ Holden, etc.
And if you haven't noticed, my constant use of the word "classic" has been in the context you are referring to: definately, the E20 BMW, Datsun Skyline GT-R 2.0L PGC-10, and XY Falcon GT are classics. I use "classic", "old" and "new" as basic names for the eras I'm talking about - use of the words' connotations, not their denotations.
Like you said, old cars are just old. But they are valued for different reasons - not their contribution to the evolution of the automotive industry (if any, really). For example, the AE86 Sprinter really pioneered nothing, it was Keiicha Tsuchiya that exposed its strengths as a drift car. And that's what it is valued for, as an old car - not a classic.