Wolfsburg Edition Golf R

[AdamD]

I think any car between August 2016 - July 31 2017 would be MY17.
So anything between August 1 2017 and July 31 2018 would by MY18.
That's how I understand it anyway.
August starts the next year's build

This is incorrect.

For Volkswagen, the next model year starts between BW21 and BW26 depending on the specific year and the model line. Either way, MY18 builds usually start around mid may of 2017. Week 21 this year started May 22nd.

Build year is build year. If it's built 31 December 2017, it's a "2017 build". Next day, it's a "2018 build".

Compliance date is the date that the compliance plate is stamped to the vehicle (at or near the docks), usually by Patrick's. So, that's after the car has arrived in Australia and typically 2-4 weeks prior to delivery.

And lastly, there's date of first registration.

The only real contention around any of the above is which value (model year, build year, compliance year or year of first reg) is the 'overall' year for the purposes of resale. Model year is certainly separate, as it's a factor of the model (redbook.com.au always lists both MY17 and MY18 options for a "2017" vehicle, for instance). However, car dealers usually go with build date when offering you a price for your vehicle, as it's always the earliest/oldest date, but it's also the most definitive value of how old the car actually is.