It appears most of the high revving V8/10/V12 engines do use Mobil 1, 0W40. I'm not sure what makes the S65 so different that it has to use such a thick oil, especially when you consider the tight clearances BMW is known for.
FWIW here's a list of cars with high revving engines that use Mobil 1, 0W40.
1. Audi RS4 V8 - 8200 RPM
2. Lambo LP 560 Gallardo - 8500 RPM
3. Lambo Murcielago - 8000 RPM
4. Ferrari 458 - 9000 RPM
5. Ferrari 599 GTO - 8400 RPM
6. Porsche 997 GT3 - 8400 RPM
7. Audi R8 V10 - 8700 RPM
8. Audi R8 V8 - 8250 RPM
9. Porsche Carrera GT - 8400 RPM
10. Lexus LFA - 9000 RPM
11. McLaren MP4-12C (TT)-8500 RPM
I know they aren't high revving engines, but they are known for big power of course and according to Mobil 1's website the Buggatti Veyron runs Mobil 1 0W40 as well as the Nissan GT-R.
http://www.mobiloil.com/USA-English/...d_Mobil_1.aspx