After it introduced the 2013 Mercedes SL63 AMG less than a month ago, Daimler is now officially presenting the even more powerful SL65 AMG variant.
In
this case we are talking about 630 HP and 1000 Nm of torque generated
by a 6.0-litre V12 biturbo engine, which despite being more potent,
(+18 HP), it is also 17 percent more efficient that before as it
requires 24.4 mpg in a combined cycle.
Some of the measures that
were taken in order to make the 6.0-litre V12 engine more powerful
include revised turbochargers with an increased spiral cross-section,
new manifolds and wastegate ducts and a new engine management system
with higher performance and optimised cylinder heads.  
The
improved efficiency figures result from the fact that the new SL65 AMG
weights 170 Kg less than before (1950 Kg in total), while in terms of
performance, Daimler claims that their range topping roadster can sprint
from 0 to 62 mph (0 to 100 Km/h) in just 4.0 seconds (0 to 125 mph in
11.8 seconds), and attain a limited top speed of 155 mph (250 Km/h).
For
the first time AMG has combined the 6-litre V12 biturbo engine
with the AMG SPEEDSHIFT PLUS 7G‑TRONIC 7-speed automatic transmission,
which apart from playing its role in the achievement of the above
mentioned performance and efficiency figures, also enables the person
behind the steering wheel to switch between four driving modes which are
Controlled Efficiency (C), Sport (S), Sport plus (S+) and Manual (M).  
The new SL65 AMG also comes with an AMG sports suspension based
on the Active Body Control fitted on the SL63 AGM, newly developed
electro-mechanical AMG
speed-sensitive sports steering and the optional MAGIC SKY CONTROL
vario-roof.
The 2013 Mercedes SL65 AMG will go sale in September, with prices starting at 236,334 Euro in German.

Source: Mercedes