It would be interesting to see VAG warranty claim statistics by brand to see if they support your line of thought.
Warranty Direct’s reliability index for the Audi A3, Seat Leon, Skoda Octavia and VW Golf paints an interesting picture. The higher the reliability index, the less reliable the car;
Audi A3; ave age 5.27 years, ave mileage 56.899, reliability index 139
Seat Leon; ave age 5.04 years, ave mileage 53,333, reliability index 166
Skoda Octavia; ave age 5.12 years, ave mileage 55,059, reliability index 95
VW Golf; ave age 3.82 years, ave mileage 46,838, reliability index 91
The average age and mileage of vehicles in the Warranty Direct stats for the Audi, Seat and Skoda are very similar so comparing these three against each other is probably a valid comparison. The average age of the Golf is
lower, with a
lower average mileage, which probably explains the higher reliability index, as cars generally become less reliable as they get older.
High level summary stats don’t tell the whole story, so should always be taken with a pinch of salt as there will be other factors that could have a bearing on reliability. However, with the Octavia having a better reliability index than a similar age and mileage A3, this suggests there isn’t a pecking order for components and parts within VAG, based on the manufacturing quality of those components and parts, otherwise the Octavia would have a poorer reliability index than the A3.