I think the argument of knowing the car better than the service advisor goes both ways. Understandable that the advisors and mechanics won't be aware of every little issue and TSB, but some of them don't like to be guided. When my Mustang went in for a clack from the rear end, I left a note on my observations and findings because I know finding noises are probably one of the worst things to fix. I told them I thought it might be the LSD (Limited Slip Differential) due to the things that instigate the noise. I made the mistake of watching the
dashcam footage after and their lead technician basically called me an internet jockey and that these are things I heard on the internet (to coin my term, driveline lash). To top it off, he thought the noise was coming from the front end. From that point I lost all confidence and ditched the car, too many stupid issues and a tremendous rattle trap to boot.
My attempts to have the sunroof in the Stinger rectified are well documented in threads here and to surmise, it was a large contributing factor to my not keeping the car. The fact that the corporate level refused to acknowledge it as a problem lead me to believe the warranty wasn't worth much if they don't fix customer complaints.
I have had a check engine light in the BMW since last week, I attribute it to the fact I had an open cone intake and the fact it was -30C for a week straight. I called to book it in to have it checked out and they blame the cold and the battery (over the phone). I'm certain the battery is fine, and the 2 hours straight of driving on Saturday should have topped up the charge completely. I've been on the factory airbox since Thursday so it should have reset by now. They'll be eating their words when the scan the codes and find the lean operating code I found, and nothing to do with the battery. I only mention this because I chose not to volunteer my findings, I feel it's only going to hurt my cause here. Since I had a very minor mod (intake) installed, I think it's just better to play dumb and get them to clear the code and/or check the vacuum lines if there really is an unmetered air leak.
Sometimes guiding the dealership helps, but others seem to take offence or don't take you seriously. There is probably a negative perception that customers "Google" everything and know nothing, likely some truth to that, though.