In my experience with tech-heavy luxury vehicles like BMWs, dealerships have a relatively small time window from when the vehicle is introduced to when their kn

In my experience with tech-heavy luxury vehicles like BMWs, dealerships have a relatively small time window from when the vehicle is introduced to when their knowledge about that vehicle drops off sharply. For example, I would trust a BMW dealer right now to work on a 2018 car, but I would take a 2000 car to an independent specialist. One reason is turnover in dealer mechanic staff. Independent specialists tend to be more stable and have a genuine interest in and affection for the older cars of a particular brand. Another reason is that most new luxury brands are highly focused on leasing brand new cars or getting customers to trade in on the latest model. They really only want to sell brand new cars at the top of the depreciation curve. People who own older cars will usually not buy them from the dealer and tend to not use dealer mechanics (often because the dealer is the most expensive option around). So dealer mechanics see less older cars, and service managers largely don't consider owners of older cars to be good/profitable customers that they need to keep happy. A related issue that causes poor experiences like you describe is the "book time" job scheduling/pay system used by most dealer mechanics. This system favors a "parts swapping" approach where mechanics try to fix problems by quickly installing new components with a minimum of diagnosis time. This gets expensive for the customer due to dealer parts costs and strongly disincentivizes thoughtful, time-consuming diagnostic procedures and research. There is also usually an informal seniority system in dealers where the senior mechanics will take the easy "gravy" jobs that can be completed quickly but cost a lot. Junior mechanics will get stuck with the difficult, hard to diagnose jobs that suck up a lot of time and reduce a mechanic's earning potential. So you end up getting the least qualified mechanics working on tricky, unprofitable issues like yours. To be fair, these issues aren't exclusive to high end vehicles, but they are especially noticeable at this market segment.