It was so much related to the Opel? I would rather have said expensive Fiat Croma (though that there was a real difference in quality even if some parts are compatible)

The Type Four chassis, upon which the 9000 was based, was shared with the Fiat Croma, Lancia Thema and the Alfa Romeo 164. The Fiat and Lancia looked much like the Saab, but the Alfa Romeo only shared the chassis. Because they were very similar, many parts can be exchanged between the four cars regardless of brand. For example, the doors from the Fiat Croma fit directly on the 9000, but are lighter, due to less side impact protection. The windshield from the Croma can also be used on the 9000. This type of windshield gives a safe driver visibility.