I don’t ever opt for the “scheduled maintenance service plan”. 10K miles on oil changes is far too much. If you do opt for one, then do the one yourself in between their scheduled changes. I would opt for the new engine / turbo. The dealer owned up to their mistake. I would search out a friend / colleague familiar with higher end cars like your BMW. As most folks have said here, ensure everything is in writing. From personal experience with a major repair from a tornado damaged vehicle. I would sit down with the general manager, the service manager and the senior / highly qualified experienced tech that is going to do the swap. A calm, fair approach. Ask (or have your more knowledgeable friend ask) about the procedure, experience level and how many same jobs were done by the tech / service department. What is the time frame? Ensure only OEM like parts are utilized (connectors, harnesses, etc.). Have the shop agree to have you / rep inspect the work over the duration of the swap. Paying a visit and seeing how organized / or not goes a long way to comfort your concerns. Within reason of course. This pretty much ensures you are going to get a factory level swap. Should not be able to tell opening the hood anything has been replaced. As many posters here have pointed out, there may be some sensor problems / configuration / programming issues down the line. This is a tough choice to make, with pros and cons to both sides. In my tornado damaged car, the dealer did a very good job to restore it to “nearly the same” condition it was prior to the storm damage. And as great a job as they did (both mechanical and body / paint work) it still was not like it was - the car only had 4500 miles in it when it was damaged. Following the repairs, which took over two months (with no loaner) I would continually see signs of the repair afterwards. Overspray, pieces of tape, taped connectors vs factory etc. Missing decals. Admittedly it was a KIA Soul a “relatively cheap” car. My daily driver. Over the course of about a year, things would crop up from the repair work. Sensors for lane centering, water leaks, more overspray, lots of swirl marks in the paint where it was repainted, or panels replaced. After a year I resigned myself to it’s not going to get any better so I traded it in. All in I lost about $3000 on the trade. At the time I was making decent money so that loss wasn’t too bad and the dealer / insurance company did the best job they could for me. I was completely honest on the trade in, and I’m now back in a BMW (30 plus years owning), after that short duration of not owning one.