AMG's new V8 makes the S63 a greener, faster übersedan

2011 Mercedes-Benz S63 AMG(Photo: Jeremy Sinek)

Stuttgart, Germany - It seems to be a habit at Mercedes-Benz to debut all-new engines in not-so-new cars. Case in point, AMG's new V8. Although the next-generation S-Class is expected for 2012, the all-new mainstay engine from Benz's performance division couldn't wait, and is having its coming out in the lightly revised 2011 edition of the current S-Class.

Another Mercedes tradition seems to be that any correlation between model designation and engine displacement is purely random. The V8 in the outgoing S63 actually displaced 6.2 litres. The 2011 replacement is still badge S63, yet its new engine is a 5.5-litre.

Gallery: 2011 Mercedes-Benz S63 AMG

Don't worry, smaller does not mean weaker. Twin turbochargers and direct injection supply heaps more power and torque, yet fuel consumption (according to European standards) drops more than 25 per cent. Carbon dioxide emissions limits are getting tighter in Europe, and this new M157 V8 underpins AMG's 2008 vow to lower its fleet emissions 30 per cent by 2012, and another 20 per cent by 2015.

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AMG does its own thing with Benz engine

2011 Mercedes-Benz S63 AMG interior(Photo: Mercedes-Benz)

The M157 is not a rework of AMG's in-house 6.2-litre V8 (M156), but an extensively AMG-modified version of Mercedes-Benz's recently-revealed new-generation V8 engine family. Outputs of 536 horsepower and 590 lb.-ft. of torque represent gains of 19 hp and 125 lb.-ft. respectively over the naturally-aspirated 6.2. An available Performance Package further boosts those outputs to 563 hp and 664 lb.-ft.

Also new to the S63 is AMG's Speedshift MCT transmission, first seen on the SL63 and extended last year to the E63 AMG. Not to be confused with the SLS supercar's dual-clutch automated manual (which cannot handle the torque of the biturbo 5.5), the MCT is essentially a conventional seven-speed automatic, but with a multi-plate clutch replacing the usual torque converter.

Banishing the torque converter saves gas, while further savings are realized by the stop/start function active in the transmission's default "C" (Controlled Efficiency) mode. As well, in C mode, the S63 always takes off in second gear, and upshifts early. More fuel is saved by generator management that delays battery charging for when the car is decelerating, letting kinetic energy do the work instead of the engine - in effect a small-scale version of what hybrids do.

That said, expect smaller gains on the Canadian federal test cycle, which provides fewer opportunities for stop/start to contribute.

Very, very quick, yet not as quick as it could be

1971 Mercedes-Benz 300 SEL 6.3 AMG race car(Photo: Jeremy Sinek)

The S63's claimed 0-100 km/h time is 4.5 seconds, or 4.4 with the Performance Package. The latter, incidentally, matches that of the continuing S65 AMG, which makes 600 hp and 738 lb.-ft. (!) from its twin-turbo 6.0-litre V12, but has only five gears in its transmission. In a confusing embarrassment of riches, the 2011 range also still includes the S600, propelled by a 5.5-litre twin-turbo V12 that makes less power (510) but more torque (612) than the regular S63, for a claimed 4.6-second 0-100-km/h time.

Does it strike you as odd that such large variations in power and torque make so little difference to 0-100-km/h times? A large part of the explanation is that all the aforementioned models are rear-wheel drive. Beyond a certain point, two wheels simply can't muster enough traction to effectively deploy all the available horsepower in first and second gears, forcing traction-control systems to dial back the power and/or brake the rear wheels.

Beginning with the next-generation S-Class, however, expect to see Benz's proven 4Matic all-wheel drive system (or a version of it) extended to the AMG models.

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This is only the beginning for the biturbo V8

2011 Mercedes-Benz S63 AMG biturbo badge(Photo: Jeremy Sinek)

As well, expect the new V8 to gradually replace the 6.2 in other AMG models, with the exception of the SLS (whose DCT gearbox can't handle the torque) and the current C63 (which we're told doesn't have room under the hood, and doesn't need that much power anyway).

Before letting us loose on public roads, our Mercedes-Benz hosts used the S63s to demonstrate the S-Class's other 2011 headliners: an available Advanced Driving Assistance Package (let's call it ADAP); and a Bang & Olufsen Performance Surround Sound System.

ADAP adds active corrective action to two driver-assist technologies originally introduced last year in passive form; previously they only warned the driver, now they also take corrective action if the driver doesn't heed the warnings. Active Blind Spot Assist firmly but gently steers the car back into its own lane if the driver, after ignoring visual and audible warnings, persists in pursuing a lane change that would cause a collision with a vehicle alongside.

2011 Mercedes-Benz S63 AMG Active Lane-Keeping Assist(Photo: Jeremy Sinek)

Active Lane-Keeping Assist takes charge if it senses the car is drifting across a solid white line and the driver hasn't responded to a warning vibration of the steering wheel. In both cases, since the S-Class does not have electric power steering, the correction is performed by braking wheels on the opposite side of the car.

The sensors are a camera for lane-keeping assist (which operates between 60 and 200 km/h) and radar for blind-spot assist (30-200 km/h). Brief demonstrations on an airport runway (against a surreal backdrop of U.S. paratroopers dropping in on an adjacent field) indicated that both systems work as intended. They can also be switched off if desired.