[ucla95]

I know of one dealer that's advertising $5000 off their in-stock M5's. I too am surprised at the lack of interest in the car.
My guesses:
1) Performance SUVs just continually becoming more popular than sedans in general, and especially at this price point.
2) S6/7 has beaten the M5 in at least one comparo and is $20,000 less. While the M5 is the better track car - I think people with a track focus are buying a GTR, M3, or 911 over an M5 - leaving the M5 kind of stuck in the middle perhaps. Not enough track performance vs other cars, and perhaps in many minds not as good as a daily-driver performance sedan as the S6/7. Remember that >50% of the sedans sold in the USA are AWD.