Well, I prefer to pay attention to what manufacturers say rather than the unsourced opinions of people on the internet . (FWIW I agree with dsl MYs should only apply if there's a visible difference that makes it the next year and until recently 'next year's model' would not be released until late on in the year. I'm also not sure we would notice most of the minor changes made for a new model year cf that Vauxhall link).

So, is it the case that French model years were based around dates of registration rather than anything official from a manufacturer? So a car built in 1999 unregistered until July 2000 would be a 2001 model under this French system? That definition is quite different from the car industry definition of a model year (it seems to be a date of registration to me) and might explain why it was abolished.