Which model year?

That's a weird one, I know, but is there a way to find out what model year a certain car is? Some look at the little number on each glass surface, others subtract a decade from the date mentioned for airbag check, and god knows what else... I am not sure if my R is a 2003 or 2004... Or if the R model was even introduced before 2004. I also saw somewhere that the mirrors were different before MY04m from the current styling. Any ideas please?
TIA

ACG