by Teddy Field
Due to arrive at the 2012 Frankfurt Motor Show in September, the 2012
Mercedes AMG SLK55 has an entirely new engine that would make a
mechanical engineer’s head spin.
In decades past, AMG was known for taking an ordinary Mercedes Benz, and
turning it into a flamboyant asphalt athlete. Rock stars, actors &
basketball players adored them, but they bought an AMG Mercedes for the
arrogant styling, and the tire-melting performance. Gas mileage had
absolutely nothing to do with their purchase decision.
In 2011, you practically need a home equity loan, just to fill up
your gas tank. So an expensive muscle car that measures fuel economy in
Feet-per-Gallon no longer makes sense. However, the
road-rocket-scientists at AMG have devised a way to combine the power of
a nuclear reactor, with the fuel consumption of a lawn mower. And
they’ve managed to do it using a non-turbo V8!
Based loosely on the turbocharged 5.5-liter V8 found in other AMG
models, this new powerplant ditches the turbos, in favor of some
Similar to the Chrysler HEMI cylinder deactivation system, the 2012
Mercedes SLK55 AMG can run on just 4 cylinders, until you tromp the gas
to get around the odd Z4 or Porsche Boxter. But this system is sheer
genius compared to the Dodge system. With the transmission in mode ‘C’
(“Controlled Efficiency”), the cylinder deactivation system is available
from 800 – 3,600 rpm, and an icon on the gauge cluster informs the
driver if cylinder deactivation is turned on, and if the engine is
running on 4 or 8 cylinders.
In 4-pot mode, there’s 170 lb-ft of torque available. But, if you
flatten the Go-Pedal, all 8-cylinders will erupt, spewing
415-horsepower and 398-torques all over the back wheels (a considerable
increase over the 2011 Mercedes SLK55 AMG).
The new Controlled Efficiency system takes just 30 milliseconds to
switch the 2012 SLK55 from Rain Forest-mode to Messerschmitt mode. At
which point the active exhausts will open, unleashing an un-holy melody
of mechanical violence.
To operate, the system uses a complex
oiling system, a NASA-grade engine management system and 16 hydraulic
actuators integrated into the cylinder heads. When the computer decides
to switch the engine back to rain forest mode, the actuators close the
exhaust & intake valves on cylinders 2, 3, 5 and 8. The computer
also deactivates the ignition and fuel supply to those cylinders.
All of that results in an estimated 18 city / 28 hwy, based on Mercedes claimed 30% increase over the 2011 Mercedes SLK55 AMG.
The latest rage in European engine design is the Start/Stop function.
And of course, it comes as standard equipment on the new SLK55 AMG.
This fuel conservation program shuts off the engine when you come to a
complete stop, then starts the engine back up (always in 8-cyl mode),
when you press the gas. Start/Stop can however, be defeated in any
driving mode, including the “C” mode.
Thankfully, the 2012 Mercedes SLK55 also has regenerative braking
to charge the battery every time you hit the brakes. A handy feature,
especially when you consider that the battery has to power all of the
onboard electronics & air conditioning while you’re in Stop mode.
Then it has to re-fire the engine when you hit the Go-Pedal.
Captain Obvious says “Don’t buy the cheap AutoZone battery”.
All of this mechanical witchcraft is controlled by a Bosch engine
control unit (computer), which is capable of executing up to 260 Million
functions per second! That’s like having an army of German engineers
inside your car, fiddling with stuff until it’s “just right”…every
Besides the electronic wizardry, the new AMG 5.5 features some unique
mechanical modifications including: a compression ratio of 12.6:1,
aluminum pistons with carbon-coated piston rings to reduce internal
friction, cylinder liners with a mechanical surface treatment called
“Spectacle Honing”, special ventilation holes in the crankcase, 5 main
bearings with 8 counter weights, 4 valves per cylinder (Captain Obvious
says that’s 32 valves total) with continuous camshaft adjustment, for
optimal fuel burning at any RPM. These adjustments are controlled by the
Omnipotent engine computer, via 4 electromagnetically controlled
Can you imagine having to fix this thing in 30 years? You’re going to
need an Engineering Degree from the University of Hohenheim.
Regardless of its complexity, the new 2012 Mercedes SLK55 AMG is sure
to set the performance benchmarks in its class. The BMW Z4 Xdrive35i,
the Porsche Boxter and the Audi TT don’t offer fuel efficient, 400+
horsepower V8’s. And none of those cars have the spine tingling exhaust
note, or the sheer Grin-Power of an AMG tuned Merc. So you can bet, this
new Eco-AMG will sell just fine.