Jouw constatering zal kloppen, daar twijfel ik niet aan.
Ik vond nog wel deze link:
http://www.glastek.com/auto-glass-faqs.html
En daar staat o.a. dit stukje tekst:
What is the difference between dealer/factory glass, OEM (Original Equipment Manufacturers), and aftermarket glass?
Many OEM auto glass manufacturers produce the glass for the automobile makers. Therefore, an OEM auto glass manufacturer such as LOF, PPG, Mopar, Carlite, and Guardian may hold the original windshield template for the automobile producer. This means that the template used for manufacturing the windshield are too the exact "original" specifications. The OEM auto glass manufacturer produces these windshields for the auto producer with the dealer insignia (GMC, Nissan, Ford, Toyota, Chevy, Dodge) in the bottom corner and send them back to the car dealer for resale. These auto glass OEM manufacturers will also use the "same original" template to resale to the public with their "own" insignia (Pilkington, PPG, Guardian, Mopar, Carlite). Most OEM auto glass manufacturers cannot resale the windshield back to the public with the “dealer” insignia. Therefore, the windshield could be the "same" original template manufactured part with a different insignia.
Now an aftermarket glass is a windshield that is manufactured to the exact manufacturer guidelines (same color, thickness) without the "original" factory template. The template specifications are recreated using a factory windshield through the means of reverse engineering. This means that the template is recreated by the measurements of the windshield and not by the original template that the dealer manufactured supplied. With today’s technology, this method has very accurate results and the strength and thickness of the glass is regulated by FMVSS (Federal Motor Vehicle Safety Standards).
Heb nog even gekeken, ik heb er nu een Guardian ruit in zitten, dat is dus een van de OEM glasfabrikanten.
Edit: Maar het kan zijn dat die niet de Volvo mal bezitten, en dus de mal hebben gemaakt aan de hand van een originele ruit. In dat geval kan ik me afhankelijk van de glasfabrikant voorstellen dat de pasvorm kan afwijken. Maar de ruit dunner maken zou de veiligheid beinvloeden. Het lijkt me dat dat niet het geval is....