There don't seem to be any changes under the hood as both models retain the same powertrains with the S63 featuring a 518HP 6.2-liter naturally aspirated V8 engine and the S65 a 604HP twin-turbocharged V12. Official details and photos are to be released during this month's Shanghai Auto Show in China where both models will be making their world premiere.
Source: Mercedes Configurator , Via: C&D