Congress Extends Ethanol Tariff to 2009
Nissan Announces Green Program 2010; Aggressive Plan Includes Clean Diesel, Fuel Efficiency, Hybrids, Plug-in Hybrids and EVs

Mercedes Introduces New High-End V8 Diesel for S Class

Mercedes-Benz is extending its S-Class range with another diesel variant, the S 420 CDI. The new eight-cylinder model is powered by a 4.0-liter V8 CDI engine developing 235 kW (320 hp) of power at 3,600 rpm and 730 Nm (538 lb-ft) of peak torque from 2,000 rpm.

This latest addition to the model line-up means that the luxury sedan range from Mercedes-Benz now encompasses two diesel engines, six petrol models and two body variants, along with the new 4MATIC all-wheel-drive system. The new S 420 CDI is available to order now, with deliveries to customers due to start in December 2006.

The S 420 CDI powers from 0-100 kph in 6.6 seconds and has a top speed of 250 kph (155 mph), with fuel consumption figures of 9.4 to 9.6 litres of diesel per 100 kilometers on the NEDC cycle (24.5 to 25 mpg US).

That makes the S 420 the second-most fuel efficient vehicle in the S series, behind the V6 S 320 CDI, which, with 173 kW (235 hp) of power and 540 Nm of torque consumes between 8.3 to 8.6 l/100km (27.4 to 28.3 mpg US). The closest comparable gasoline vehicle in the series—the 4.7-liter V8 S 450 (250 kW and 460 Nm) consumes 11.2 to 11.5 l/100 km (20.5 to 21 mpg US) of fuel.

As another point of comparison, the hybrid powertrain in the Lexus LS 600h L combines a new 5.0-liter gasoline direct-injection V8 with large, high-output electric motors and a newly-designed battery pack to deliver more than 330 kW (442 hp) of total system power with fuel consumption of less than 9.5 liters/100km (more than 25 mpg US). (Earlier post.)

In the S 420 CDI, third-generation common-rail high-pressure injection technology with a maximum injection pressure of 1,600 bar and an ignition pressure of 175 bar contributes to efficient combustion. Optimized flow dynamics for the best possible gas cycle and twin turbochargers with variable-nozzle turbines support high power and torque delivery.

As many as five injections of diesel fuel per injection cycle, special orifice nozzles, piezoelectric injectors and highly effective exhaust gas recirculation all help to lower emissions significantly.

The new V8 powerplant is equipped as standard with a maintenance-free diesel particulate filter to cut untreated emissions even further, and also complies with the Euro 4 emissions standard. The engine development team was able to reduce noise levels by optimizing the chain drive and fitting a rigid crankcase with large engine bearings as well as extra acoustic covers. The square bore-to-stroke ratio combines with a counter-rotating balancer shaft for outstandingly smooth operation.

The engine is mated with a seven-speed automatic featuring a wide ratio spread.



It would be nice to hybridise that so you could crawl through heavy traffic in electric drive, then open it up on the Autobahn.
In fact, it would be nice to hybidise most things, if it did not cost too much.
Luxury cars such as these could bare the extra cost, whereas a Yaris might be overwhelmed by it.

A GM head once said that if you use your marketing budget for hybrid development, you get much better press than if you spend it on conventional marketing.

It would be very nice to build an "E-crawler" version of this (and other) cars.


In Germany, an S 420 CDI costs $23,000 more than an S320 CDI, but shaves only 0.9 secs off the 0 to 62 mph time.

If Mercedes offers a 2-mode hybrid transmission on a 2008 S 500, adding at least 50 bhp and 10(?) mpg, why would I want a 420 CDI?

If they offer a hybrid 2008 320 CDI in California with Bluetec 'particulate control', why would anyone want a 420 CDI? An S 320 CDI does 148 mph in European trim, which should be enough for a large sedan, even in Germany....


One of the main advantages of diesel is very high efficiency at low loads. Therefore you don't get the same benefit hybridising a diesel as you do with a petrol.


Hybridising diesel vs gasoline.

Perhaps, but it would be very nice from a pollution point of view to have diesels OFF when crawling in traffic.

As more people use diesels (i.e. in Europe), this will become more important.

You could drive the rear wheels electrically (not in the mercs) and the front wheels from the ICE (or vice versa).

Keep it simple, keep it cheap to build - or am I missing something.


V8 engine with balance shafts. Max power at 3600 RPM, mated to 7-speed automatic. Two ton RWD luxury car with economical 320 hp engine. Environmentally friendly Euro 4 diesel. Only for 100 grands.

Quite a statement. Sounds like “proud to be a moron”.

tom deplume

Two variable nozzle turbos and a 7 speed automatic trans. So much complexity for so little gain in efficiency.

Rafael Seidl

Gents -

there is a small percentage of extremely well off people that want their car to proclaim just how ludicrously loaded they really are. In a civilized, understated way, of course. The S Class Merc is a favorite among Saudi Princes and Japanese Yakuza as well. Those guys really could't care less about fuel economy, it's all about projecting power and status.

The ride is nice enough, I suppose, but nobody really needs more than six cylinders to get from A to B. Audi has announced it will bring a 12 cylinder diesel to the Q7 in Europe in 2008. That is truly insane, but I suppose those who buy high-end SUVs do so precisely because they are an indulgence.


The V12 TDI engine from Audi will deliver: 500 HP and,
more impressive, 811 lb-ft of torque !!
( 811 lb-ft = 1100 N-m of torque )

That is more torque than that delivered by some city buses !!



I have nothing against rich-people wheeled-Rolex toys. It is the mix of controversial technical features which is just silly.

6 cylinder engines are inherently balanced and have lowest possible noise/vibration. Turbocharged gasoline engine is the most powerful one. RWD, highly prized for its racing cornering, is useless on luxury car with long wheelbase, soft suspension, and heavy weight. 3600 RPM engine requires no more than 4 speed transmission. Diesel engine emits more health harming emissions than gasoline.

If one want extreme off-road hauler, there is diesel Hummer (real one, favored by one of your countryman). For light-weight off-road there are Samurai and Sahara. For extreme street performance there are AWD line of STI, Evo, and Skyline. For luxury performance there are Porsche, and plentiful –i line: Masarati, Lambordgini, Bugatti, Ferrari ( mid-engine, short wheelbase, RWD, overpowered beasts). Luxury sedan is best presented by aluminum-body, variable suspension, AWD Audi A6/A8.

With all due respect to Merc’s technical sophistication, this car is just a horrible mutant.


I think that the point of this powertrain is to offer a best in V8 class driving range, and a "wheee" factor when test driving the car. Like so much bling, this is how the luxobarge market is rationalized. For these types, stopping for fuel is a risk to be minimized.


The first official car as you all may recall is the Benz patented in 1886. So if they want to build a V8 diesel car that is quite brilliant let them be. If you have any negative comments please make sure you have purchased one and then complain!

The comments to this entry are closed.