- 2018–2019 Factory-verified
only in: Sportback; 2019: Regal, Preferred: S (2019 Sportback order guide); letter O in the code as GM prints it; GM prints no zero form
IOR Factory-verified
Also documented for ChevroletGMC
Documented applications
This page aggregates every documented appearance of IOR in the Buick reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.