I think he is asking how to ensure a model year 2017 that was sold originally in sept of 2016 is actually a 2017
Or maybe is it legal to consider s car sold in 2016 to be a 2017?
I suspect the op is not understanding than a 2017 model year can legally be produced as early as January of 2016 and it still be considered to be a 2017 (model year). The fact that most people drop off the term “model year” is what confuses the situation.
Year of manufacture and model year are not exactly concurrent.
So, a car produced in 2016 can be considered a 2017 on the registration as the registration reflects model year and not the actual date of production. If he wants to know the date of production, refer to the data plate on one of the door jambs. If he wants to know the model year, refer to the title. The model year can be confirmed by deciphering the VIN as it includes the model year within its cryptogram.