Personally I think retro is in the eye of the beholder.
I kind of get the '20 year' cut off point, but I think anything older than 15 years could be considered retro or a modern classic.
The one thing that really bugs me is people calling 'classic cars' vintage, that's a whole other discussion but I'd say vintage needs to be pre 1930's - maybe time will shift to include 1940's models in the vintage classification.
Absolutly yes. And the mention of 'modern classic' is a welcomed can of worms and gives me something I think I can hang on my Cube . I get the vintage thing too, its like when people call items antiques when they arnt even 100 years old.