Got my car back after 2 days at the dealer. It was diagnosed as a faulty camera module draining the battery, leading to all sorts of error messages.
Dealer changed the module, reset the software to the "latest" applicable release, and the car did seem to have gotten the old oomph back.
Maybe the faulty module was the reason for 3 battery changes in 3 years.
We'll see how well this fix holds up.
I am convinced, that these cars should not be owned when the warranty runs out. My 7 year old 330CiC works like a champ. But this car will be traded in as soon as the warranty runs out.
2012 Lexus LS460, 09 750i (sold), 06 BMW 330Ci, 03 MDX, 08 535i (Sold), 73 Piper Cherokee (sold), 82 Yamaha 750 (sold) Too many Audis, Mercedes-Benzes, and other Lexuses to mention.