One problem related to visibility has been reported for the 1999 Buick Century. The most recently reported issues are listed below.
Interior rear-view mirror has developed some kind of dark brown oil leak inside the (auto-dimming) mirror. It has decreased visibility in the mirror to nearly zero. It is very dangerous to drive with this mirror since it is essentially like having no rear-view mirror. Just today I had two or three near-incidents on roads I never had a problems while driving other cars which have functioning rear-view mirrors.