As the 2012 Beijing Auto Show is right around the corner, Daimler has decided to make things official and release photos and details regarding the 2013 Mercedes G63 AMG and G65 AMG models ahead of their public premiere.
The new G63 comes with a few noticeable design upgrades, such as an aggressive looking front bumper, a new grille, newly designed alloy wheels and a side mounted exhaust, and also "a raft of
future-oriented systems" such as spray-controlled petrol direct injection, the
ECO start/stop function and generator management.
The 5.5-litre V8 biturbo engine fitted on the 2013 Mercedes G63 AMG develops 544 HP (400 kW) and 760 Nm of torque via an AMG SPEEDSHIFT PLUS 7G-TRONIC transmission, (+37 HP and +60 Nm if compared to the G 55 AMG KOMPRESSOR), but even thought it is more powerful, it requires less fuel per 100 Km – 13.8 litres to be exact (20.4 mpg, UK rating / combined cycle).
CO2 emissions reach 322 grams per Km, while in terms of performance the 2013 G63 AMG can sprint from 0 to 100 Km/h (62 mph) in 5.4 seconds and reach an electronically limited top speed of 209 Km/h (130 mph).
As for the 2013 Mercedes G65 AMG, in this case power is extracted from a 6.0-litre V12 biturbo engine featuring new turbochargers, multi-spark ignition, twelve double-ignition coils and a higher-power engine control unit, which sends 612 HP (450 kW) and 1000 Nm of torque to all four wheels also via an AMG SPEEDSHIFT PLUS 7G-TRONIC transmission. 
This new model also comes with new suspension/damper settings, optimised acoustic comfort and completely new brakes (all-round ventilated, perforated discs measuring 375 x 36
mm at the front and 330 x 20 mm at the rear).
The new G65 AMG goes from 0 to 100 Km/h (62 mph) in 5.3 seconds, reaches a limited top speed of 230 Km/h (142.92 mph) and its consumption and emission figures are 17 litres per 100 Km and 397 g/Km of CO2.
What differentiates the G65 AMG from the G63 AMG in terms of appearance is the high-gloss chrome radiator grille, the 20 inch five-spoke design alloys and the V12 BITURBO logo on the mudguards.
Pricing for the 2013 G63 AMG starts at 137,504 Euros while the G65 AMG will go on sale starting from 264,180 Euros.  

Source: Mercedes