German Car Zone

Mercedes Reinvents the Mild Hybrid

It might look like an ordinary S-Class, but make no mistake, because the 2010 Mercedes-Benz S400 BlueHybrid represents a major step in the development of the hybrid luxury car.

This prototype is Mercedes-Benz's belated answer to the Lexus LS 600h L — a gasoline-electric hybrid that delivers a combined 299 horsepower along with average fuel consumption just shy of 30 mpg. It also heralds some of the most advanced battery technology ever applied to a series production car.

Don't hold your breath waiting for it, though. With Mercedes-Benz yet to complete development, North American sales aren't planned to get under way until September 2009.

As Seen in Frankfurt
You'll have already heard about the 2010 Mercedes-Benz S400 BlueHybrid from last year's Frankfurt Motor Show, where it was hailed as the forerunner of a whole range of new hybrid models being prepared by Mercedes-Benz. In fact, the hybrid drivetrain and battery pack have been developed along a modular basis, meaning they can easily be altered to suit individual models.

Mercedes-Benz acknowledges it's playing catch-up in the hybrid ranks, and project leader Oliver Vollrath tells us, "The S400 BlueHybrid is not the definitive answer to the world's long-term sustainable mobility requirements. But it does represent a big step into the future, particularly in the area of battery technology. At the moment there is no car that matches its level of technology."

You will recognize the basics from the existing Mercedes-Benz S350. Unlike the more familiar hybrid models from Lexus, however, the S400 BlueHybrid does not possess an ability to run exclusively on electric power. Instead its electric motor is used as a mechanism to permit stop-start operation of the V8 engine for improved fuel economy in stop-and-go driving, then adds a boost of power if required at cruising speed.

A Little Bit of Science

The naturally aspirated 24-valve 3,498cc V6 gasoline engine sitting up front has received a number of revisions, but it oddly does without direct injection. A new cylinder head, revised pistons and modified camshaft improve fuel economy and also raise this V6's power output to 279 hp, some 7 hp more than before. The engine is also rated at 258 pound-feet of torque.

These figures are nothing to write home about, since the direct-injection 3.5-liter V6 found in the CLS350 available in Europe delivers 12 hp and 11 lb-ft more. But the addition of an electric motor, neatly packaged at the front of the gearbox, helps provide added thrust in a car that tips the scales at 4,310 pounds.

With a potential of 20 hp and an ability to serve up 118 lb-ft of torque the moment you hit the accelerator, the circular three-phase AC unit provides the S400 BlueHybrid with a combined output of 299 hp and 284 lb-ft of torque, all of which is transferred to the rear wheels via Mercedes-Benz's seven-speed automatic gearbox and a final-drive ratio of 3.07:1.

Battery Technology

Mercedes-Benz has dug deep into its development budget to deliver a powerful yet lightweight battery pack for the S400 BlueHybrid. It features newly designed high-voltage lithium-ion cells and an associated cooling system.

The Mercedes-Benz battery solution has been engineered specifically for the demands placed upon it by everyday driving, with a new nickel/cobalt/aluminum chemical process that is claimed to provide significant efficiency and energy density gains over the nickel-metal hydride batteries that are used in just about every existing hybrid on the market today. Mercedes-Benz claims the advanced new cells used in the S400 BlueHybrid provide a much faster charge process, additional range and an overall increase in electrical efficiency.

Another advantage is the compactness of the battery design. Instead of sacrificing trunk space like many rivals, Mercedes-Benz has managed to mount its new lithium-ion battery pack (which consists of five separate cells in a high-strength steel casing) underneath the hood. It's located at the base of the windscreen in the place usually taken up by the standard S350's lead-acid unit, which it replaces.

Mercedes-Benz has developed an electronically controlled cooling process integrated into the air-conditioning system that keeps the S400 BlueHybrid's battery cells operating at an optimal temperature of between 59 and 95 degrees Fahrenheit. Altogether, the battery and cooling system uses 25 unique patents. Vollrath claims the batteries will be good for up to 600,000 cycles, or a life of over 10 years.


Full Article:

2010 Mercedes-Benz S400 Hybrid First Drive on Inside Line


M

Simply amazing.

What is the deal with MB and the 3.5 V6 engine. how many variations and different engine outputs do they need?

Boy you just asked the question of a generation. In short, no one has any idea. You have the 300hp version in the SLK350, you have the 315hp version in the SL350, you have the 272hp version in the E, RL, ML, C, CLK, S and CLS350 models, then you have (in select European countries) the CLS350 and E350 CGI mdels with direct injection and 292hp. There could be others, I don't know.

The new E-Class will likely debut another version of the 3.5L V6. I predict about 300-320hp with direct-injection and other tricks. This version will be "cooking" version for all the workhorse models like the C350, E350, R350, ML350 etc. The SLK350's version is a high-rev version, not especially suited to suvs and the like, but it still could have been even more powerul and efficient with direct-injection. The 315hp version in the European SL350 is likely just a further tuned version of the engine in the SLK350 since it doesn't have direct-injection either.

What a mess. I don't think Mercedes' R&D department knows how many versions of this engine they've got out there now either.


Hopefully next year's E350 will provide the engine for rest of the V6 lineup.


M

This latest incarnation of the 3.5 liter engine is optimised for increased thermal efficiency and low specific fuel consumption by using the Atkinson principle. Here's an info page about it:

ICE - The Internal Combustion Engine in Hybrid Vehicles

True, the direct injection engines have been long on the tooth. Development was much more difficult than initially thought. Also some issues with fuel quality and emissions may have contributed to the delay.

nice too see that the car has a full boot. This is going to be one very popular car.

i feel for the MB techs that will have to work on all these different engines.