Mechanical changes are minimal to both drivetrains, but AMG has squeezed around three per cent better fuel consumption and C02 emissions from both the mighty 6208cc V8 in the S63 and the 5980cc twin-turbo V12 of the S65.
Worry not, though; power and performance are broadly unchanged, so while the AMG boys will leave you with a little more change in your pockets at the pump, the chauffeur still has enough poke under his right foot to cause your glass of Cristal to empty its contents all over your Saville Row suit.
The twin-turbo V12 kicks somewhat harder, with 603bhp between 4800rpm and 5100rpm and 738lb ft of torque that, as Mercedes rather coyly points out, is 'reduced from 885 to 738lb ft out of consideration for the drivetrain'. Traction issues mean that getting to 60mph still takes 4.4sec, but the S65 will power on to a (still limited) 186mph top end.
Styling changes are discreet, but the AMG S-classes both get the new headlamp and 'arrowhead' grille treatments seen on the rest of the S-class range, while the AMG cars get LED daytime-running lights at the front and restyled rear light clusters (again LED-powered).
Other differences between the two AMG models include subtly different quad exhausts and a more imposing twin-louvre grille on the S65.
The cars go on sale in Germany this month, but won't hit UK dealers until September. German pricing is €115,700 (£99,000) for the S63 AMG and €185,900 (£160,000) for the S65. UK prices are likely to be near-identical.