Car Reviews: 07/16/09

Thursday, July 16, 2009

Mercedes' performance team confirm e-car plan

The speed freaks at Mercedes-Benz's tuning subsidiary and skunkworks, AMG, are preparing an electric version of the forthcoming SLS AMG gullwing über-coupé.

And here's a schematic of the beast's "SLS eDrive" power train:

Inside AMG's SLS eDrive
Click for larger version

AMG boss Volker Mornhinweg recently said the SLS eDrive is pencilled to enter production in 2015. Its petrol-powered sibling, the V8 SLS, will be officially unveiled at the Frankfurt Motor Show in September.

Unlike the V8, which makes do with power going solely to the rear wheels, the leccy version will be four-wheel drive with each wheel driven by an in-board - rather than in-wheel - electric motor.

According to AMG, the eDrive's motors will produce a combined 392kW (525bhp) of power and 649lb-ft of torque compared to the 571bhp and 479 lb-ft produced by the 6.2l V8 engine in the standard car.

Testing the SLS mule in the desert...

The SLS eDrive development will be able to hit 60 in less than four seconds and has a top speed of over 120 mph. Corresponding numbers of the V8 are 3.8s and 198mph, respectively.

The range is rather less impressive, though: between 93 and 112 miles, depending on the load placed on the motors. Presumably, AMG expects those numbers to rise – and dramatically - between now and 2015.

...and in the ice

The eDrive's batteries will sit under the floor in the space taken up in the V8 by the “torque-tube” that connects the front-mounted engine to the rear-mounted gearbox and in the space left vacant by the fuel tank.

As a footnote the SLS eDrive's lithium-ion battery pack will be supplied by German company Evonik rather than Tesla with whom Mercedes-Benz recently formed a partnership with just this sort of battery and drive train development in mind.

First Drive: 2011 Mercedes Benz SLS AMG

We're flat-out on Germany's Sachsenring race track in the new Mercedes SLS AMG, chassis number 00045, a mildly camouflaged pre-production model. Ahead is an SL65 AMG Black Series--twin-turbo V-12, 670 hp, 738 lb-ft of torque--driven by Tobias Moers, head of AMG's r&d division, seasoned race instructor and today's pace-setter. Filling his mirrors, our red gullwing keeps pushing harder and harder, even though its normally aspirated 6.2-liter V-8 is rated at a comparably modest 571 hp and 479 lb-ft. The Sachsenring has plenty of slow corners, lots of climbs and descents, two long straights and two very fast and very blind fourth-gear bends.

As our session progresses, this track is becoming a nightmare for the wide, fat SL, and dreamland for the light and nimble SLS. Despite the Black Series car's four more cylinders, 100 extra hp and 259 lb-ft of added torque, it's punished by its 551-lb weight penalty. The SLS not only uses a significantly lighter double-wishbone aluminium suspension, it also boasts a featherweight spaceframe body which tips the scales at a mere 531 lbs. Perhaps even more significant is the weight distribution. In contrast to the nose-heavy SL, the new gullwing places only 48 percent of its mass on the front axle and 52 percent on the driven wheels.

In this match, the Black Series SL doesn't stand a chance. It understeers early, and after only ten laps it has practically run out of front tires. The momentum gained on the straights can never compensate the speed lost on the approach to and through the infield.

The SLS is a totally different animal. It is 49 inches low and 76 inches wide, with cab-backward proportions that emphasize the front-mid-engine layout. The boxy light-alloy skin is draped over a long, 105-inch wheelbase. The gullwing doors open at a large 70-degree angle, but even when fully deployed, the maximum clearance is a scalp-threatening 5 feet, so that short people can still reach the inner grab handles from their seats. The power-operated buckets, which feature lightweight magnesium backrests, are comfortable and supportive. The steering wheel's squared off bottom is a bit of a nuisance through the esses, and in a car this sporty, the shift paddles should be attached to the column--not the wheel.

Electric Gullwing: Mercedes Previews a Shockingly Awesome Sports Car

Mercedes SLS AMG Gullwing Electric Drive : Mercedes-Benz and its high-performance specialist division AMG offered a first look at a prototype all-electric sports car, the SLS AMG "electric drive" is powered by four in-wheel electric motors providing 526 horsepower and maximum torque of 649 lb-ft. A liquid-cooled 48 kWh, 400-volt lithium-ion battery provides the juice. Mercedes-Benz

After a week of rumor-mill musings online, Mercedes-Benz and its high-performance specialist division AMG offered a first look at a prototype all-electric sports car. And by "first look" we mean "better use your imagination." The company released some details on a version of its upcoming SLS AMG roadster with an electric drive system. Propelling the concept car are four in-wheel electric motors providing 526 horsepower and a maximum torque of 649 lb-ft. That means, when the SLS AMG electric hits the streets -- rumored to happen in 2015 -- it'll likely be quite a performer.

Why the in-wheel motors instead of wheel-hub electric motors, as in some prototypes? Mercedes says it's all about reducing unsprung mass. The company says it's also engineered the car to have the same low center of gravity and balanced weight distribution as the gasoline-powered model. Also, a software-controlled all-wheel-drive system, dubbed AMG eDrive, micromanages torque delivery down to the individual wheel. The first prototype will get a liquid-cooled 48 kWh, 400-volt lithium-ion battery that can be charged by a plug-in system as well as regenerative braking. More details to be announced.

Aside from the technology play, the announcement is also likely calculated to attract attention to the company's gorgeous new SLS AMG sports car, set for a debut later this year. Not that the SLS needs gimmickry to win it coverage: Photos of the upcoming, high-end homage to the classic 300SL "gullwing" Mercedes of the 1950s leaked to German car magazine AutoBild earlier this week. Autobild says the SLS will get a 6.2-liter V8 engine producing 571 horsepower and 479 lb-ft of torque, able to launch it from zero to 62 mph (100 km/h) in 3.8 seconds, and up to a top speed of 196 mph. More details will likely be revealed when the SLS AMG is unveiled later this year.