AT A GLANCE:
2007 MERCEDES-BENZ SL55 AMG
ON SALE: April
BASE PRICE: $128,000 (est.)
POWERTRAIN: 5.4-liter, 510-hp, 531-lb-ft supercharged V8; rwd, five-speed automatic
CURB WEIGHT: 4285 lbs (est.)
0 TO 62 MPH: 4.5 seconds (mfr.)

This is the facelifted SL55 AMG. No, really it is. You can tell by the er, well... Okay, so the styling changes Mercedes-Benz made to its supercharged 5.4-liter V8-powered roadster are relatively minor: slightly reprofiled front bumper, three-slat grille in place of the earlier four-slat unit, redesigned tail-lamp lenses and new 18-inch wheels. Stand it next to the former model and we guarantee you will have a hard time telling the difference.

It’s underneath where all the interesting stuff lurks. For starters, the SL55 AMG’s three-valve-per-cylinder engine is reworked to deliver an added 17 hp, taking peak power up to 510 hp at 6100 rpm. Torque, always an SL55 AMG strength, also increases, topping out at 531 lb-ft between 2600 and 4000 rpm. Not exactly lacking in firepower, then. Changes to the engine include a larger throttle valve on the inlet manifold for improved breathing, changes to the management system to alter the operation of the fuel-injection system to make it cylinder selective, and there is a new supercharger unit that is claimed to be more efficient at higher operating speeds. The engine is mated to Mercedes’ five-speed automatic.

Mercedes claims 0.2 second is shaved from the 0-to-62 time of 4.5 seconds with top speed limited to 155 mph, although North American customers can pay extra to have the top end extended to 186 mph.

This SL55 AMG is a more compelling car to drive hard over challenging roads than its predecessor. The car’s overall character remains pretty much the same, but with greater control and added directness built into the chassis you find your confidence levels growing. Changes to the active body control system help rein in body movements faster and provide a more progressive action.

The steering ratio is also sharpened with new mapping and a revised hydraulic pump combined with a reworked damper for the steering rack. Along with more compliant bushings on the four-link front suspension, this improves on-center steering feel and provides sharper turn-in response. The former model’s electrohydraulic brakes are replaced by a fully hydraulic system.

AT A GLANCE:
2007 MERCEDES-BENZ SL550
ON SALE: April
BASE PRICE: $94,612
POWERTRAIN: 5.5-liter, 382-hp, 391-lb-ft V8; rwd, seven-speed automatic
CURB WEIGHT: 4202 lbs
0 to 60 MPH: 5.2 seconds
FUEL MILEAGE (EPA COMBINED): 19.6 mpg

A visible difference in the 2007 Mercedes-Benz SL coupe/convertible is a badge change from SL500 to SL550. But that simple one numeral change is accompanied by a far more substantial makeover under the hood.

That’s where you find the same powertrain launched a few months back in the S-Class, including the new four-valve-per-cylinder, normally aspirated 5.5-liter V8 that produces 382 hp and 391 lb-ft of torque—up 80 hp and 52 lb-ft over the SL500. At the same time Mercedes says the new engine provides the same 16 mpg city/24 mpg highway fuel economy as the outgoing model.

Power is routed through Mercedes’ seven-speed automatic gearbox, with the wide range of gear choices controlled by either the console shift lever or steering wheel-mounted paddles. All this combines to speed the new SL from 0 to 60 mph a full second quicker than the old model.

The monster twin-turbocharged V12-engined SL600 also gets attention, with another 17 hp and 22 lb-ft on tap, pushing output to 510 hp and 612 lb-ft. Need more? SL55 AMG gets an extra 17 hp and 17 lb-ft from the carryover three-valve supercharged 5.5-liter V8, topping out at 510 hp and 531 lb-ft.

Subtle exterior and interior changes distinguish the new model line, including new 17- and 18-inch wheels and a revised front end with a three-louver grille.

Down the road look for Mercedes to move away from supercharging when it replaces the SL55 AMG engine with a turbocharged version of the 6.3-liter V8.

AMG Fires Back at Rivals With New 6.3-liter V8
Date Posted 08-30-2005

AFFALTERBACH, Germany — Of late, AMG has concentrated on artificially aspirated engines, namely supercharged V8s and turbocharged V12s. But that's all about to change when Mercedes-Benz's performance division unveils its new V8 at the Frankfurt Motor Show next month.

Dubbed the ML156, the new normally aspirated 6.3-liter V8 will make its Frankfurt debut in the Mercedes-Benz ML63 AMG. The engine delivers 510 hp at 6,800 rpm and 465 pound-feet of torque at 5,200 rpm. AMG officials told Inside Line the large displacement allows 20-percent more torque than its chief competitors, while at the same time being lighter, more fuel-efficient and more drivable.

After it debuts in the ML63 AMG, the engine will go into the CLK63 AMG and E63 AMG, likely to be unveiled at next spring's Geneva show. In late 2006, the engine will make its way into the R63 AMG, and in early 2007, it will go into the C63 AMG and SLK63 AMG.

The ML156 engine won't be fitted into the AMG versions of the new S-Class — premiering at the Frankfurt show — the CL or SL until at least 2008. Those vehicles will feature more powerful versions of their current engines.

While this new engine is normally aspirated, AMG officials said the division will remain faithful to turbocharging where it makes sense.

What this means to you: The horsepower race continues.

The SL-Class underwent a minor facelift just last year, and already Mercedes engineers are hard at work on a new model. Spy photographers have snapped photos showing a test car with a disguised front end. Whether we're looking at a facelifted current-generation SL or a mule for an all-new model remains to be seen.



The spies at Hidden Image reckon the car pictured here is a major facelift for the 2008 or 2009 model year. They say the updated SL will get an all new front end including grille, air intakes and headlights as well as a new rear end and new taillights.



But we're not convinced. Development appears far too early along for this to be a 2008 model, which would have to be in showrooms by late summer.



So let's assume that this is a 2009 SL-Class instead. An all-new SL is expected for either that model year, or the 2010 model year at the latest. Why would Mercedes completely redesign the front of its flagship roadster, only to replace the entire car one year later?



With that in mind, we believe this is actually a test mule for the next-generation SL-Class. Automakers often graft all-new front ends and engines onto previous-generation bodies in order to complete early testing.



The current SL was introduced for the 2003 model year, meaning a replacement should arrive seven years later, for the 2010 model year. Of course, Mercedes could bring the new model a year early, as it's planning to do with the 2009 E-Class. Time will tell…

Numerous spy images have been taken of the updated SL undergoing cold-weather testing near the Arctic Circle recently. The test-mule in those images, which was actually an AMG version, looked very much like the current model expect for a new front-end that was heavily disguised. As these latest renderings show, the facelifted SL is expected to receive a totally redesigned front-end from the windshield forward.

The new car should adopt tapered back headlights similar to those seen on the current CLS saloon, with the front bar featuring a much more aggressive look with sharper angles, a new grille and larger air-intakes. Changes at the rear are minimal, with a new diffuser design and brake-light LED clusters.

The supercharged V8 engine from the SL55 AMG will likely be replaced with Mercedes’ modular 6.2L V8 for a new SL63 model. Final output will match those figures of the new S63 and CL63, with 518hp and 630Nm on tap. The twin-turbo V12 complete with 612hp and 1000Nm of torque in the SL65 range-topper is expected to remain unchanged, while the lesser SL550 and SL350 models are unlikely to adopt any mechanical changes as they were recently updated.

The facelifted SL will debut towards the end of next year or early 2009, ahead of an all-new model in 2011.