In general, the model year for Aston Martin changes following the factory summer shutdown in August of each year. It is a time that updates are often made to the general specification of a car. Sometimes updates are applied mid year which throws up partial model years such as 2016.5MY and 2012.25MY. It’s a handy way to categorize the improvements made to the cars. The 10th character in the VIN is for the model year.