Not sure why you would want to add it. Read the thread about how crappy it works regarding the "Automatic Braking" thread and "ACC" thread a few pages into this general forum. Be glad you do not have it. I have had two Denalis with it now and wish there was a way to disable it. When I ordered both of mine you could not get a Denali without it. Interestingly enough now in the 2016's the ACC is a stand alone option for $995...obviously there must be enough customers that do not want it even on upper trim rigs. Just my 2 cents.