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Mercedes-Benz Firms Up Launch of Three New BlueTEC Diesels in US; First AdBlue Light-Duty Vehicles for the US
14 March 2008
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| The R 320 BlueTEC, ML 320 BlueTEC and GL 320 BlueTEC. Click to enlarge. |
As it announced previously, Mercedes-Benz is introducing three new BlueTEC diesels—the new models R 320 BlueTEC, ML 320 BlueTEC and GL 320 BlueTEC—which will initially be available exclusively in the US, beginning in autumn 2008. (Earlier post.) The GL- and ML-class vehicles are SUVs; the R-Class is a tourer (wagon).
The diesel SUVs are powered by a 3.0L, V6 engine featuring the Mercedes-Benz BlueTEC technology for emissions control. The new models are equipped with AdBlue injection for Selective Catalytic Reduction (SCR) of NOx, and exceed the US Tier 2 Bin 5 limits. Hence, they can be sold in all 50 states.
Mercedes-Benz has developed two BlueTEC systems to ensure efficient NOxaftertreatment for different sizes of vehicles. In the E 320 BlueTEC sedan available in the US and the E 300 BlueTEC sold in Europe, an oxidizing catalytic converter and a particulate filter are combined with a particularly durable NOx storage-type catalytic converter and a special SCR (Selective Catalytic Reduction) converter.
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| The NOx trap-based BLUETEC system for the E-Class. | The AdBlue urea-SCR-based BLUETEC system for the GL-class. |
| Click each diagram to enlarge. | |
The second BlueTEC version is used for the new GL 320 BlueTEC, ML 320 BlueTEC and R 320 BlueTEC SUVs. In this case AdBlue, an aqueous urea solution, is injected into the stream of exhaust gases. This releases ammonia, of which 80% is reduced to form nitrogen and water by the downstream SCR converter. BlueTEC vehicles reduce NOx by up to 80%.
The AdBlue solution is held in a separate onboard tank, and fed to the metering module by means of a pump. As the average consumption of AdBlue is only around 0.1 liters per 100 kilometers (or 1 to 3% of diesel consumption), the tank can be of such a size that it only needs to be refilled at the workshop during regular service intervals. The tank capacity is 28 liters (7.4 gallons US) in the R 320 BlueTEC and ML 320 BlueTEC, and 32 liters (8.5 gallons US) in the GL 320 BlueTEC.
Even under more demanding conditions with a higher AdBlue consumption—e.g. when towing a trailer—this is sufficient to avoid the need for unscheduled refilling stops in the workshop. Should the AdBlue level unexpectedly fall below a certain level nonetheless, the electronics provide a warning.
In addition to the NOx aftertreatment systems, the BlueTEC systems feature optimization of the engines and their combustion processes to reduce engine-out emissions as far as possible. These measures include electronic engine management, four-valve technology, third-generation common-rail direct injection with piezo-electric injectors, a turbocharger with variable turbine geometry and exhaust gas recirculation.
Oxidizing catalytic converters are used to minimize emissions of carbon monoxide (CO) and unburned hydrocarbons (HC).
A particulate filter, which has been standard equipment in all Mercedes-Benz diesel models in many countries since summer 2005, reduces particulate emissions to a barely measurable level. This easily meets both the current EU4 particulate limits (0.025 grams/kilometer) and the current US limits.
The V-6 diesel engine powering the new BlueTEC models in the GL, M and R-Class has an output of 155 kW (211 hp) and develops torque of 540 Nm. Certain features of the Mercedes six-cylinder diesel engine were modified for use in the new models ML 320 BlueTEC, GL 320 BlueTEC and R 320 BlueTEC with AdBlue injection. The piston crowns were revised for an improved mixture formation, and the compression ratio was reduced from 17.7 to 16.5. The VNT turbocharger and engine control unit were also improved and reconfigured. All three of the new vehicles are available only with the 7G-TRONIC seven-speed automatic transmission.
| Selected Technical Specs for New BlueTECs | |||
|---|---|---|---|
| Parameter | ML 320 BlueTEC | GL 320 BlueTEC | R 320 BlueTEC |
| Cylinders | V6 | V6 | V6 |
| Valves per cylinder | 4 | 4 | 4 |
| Displacement cc | 2987 | 2987 | 2987 |
| Bore x stroke mm | 83 x 93 | 83 x 93 | 83 x 93 |
| Compression ratio | 16.5:1 | 16.5:1 | 16.5:1 |
| kW/hp @rpm |
155/210 @ 3,400 |
155/210 @ 3,400 |
155/210 @ 3,400 |
| Nm @ rpm |
540 @ 1,600 - 2,400 |
540 @ 1,600 - 2,400 |
540 @ 1,600 - 2,400 |
| Acceleration 0-60 mph s* | 8.5 | 9.2 | 8.6 |
| AdBlue tank capacity gal. | 7.4 | 8.5 | 7.4 |
| Fuel economy urban mpg* | 18 | 17 | 18 |
| Fuel economy highway mpg* | 24 | 23 | 24 |
| * provisional figures | |||
March 14, 2008 in Diesel | Permalink | Comments (23) | TrackBack (0)
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Comments
These vehicles will be eligible for regular sale in all 50 states because they meet - rather than exceed - T2B5 = LEV II.
Also, I cannot imagine the E-Class uses both a NOx trap and an SCR system. Both technologies are part of Mercedes' Bluetec portfolio, but normally only one or the other is applied to any given vehicle to clean up the NOx. The graphic provided looks misleading.
Posted by: Rafael Seidl | Mar 14, 2008 5:41:34 AM
So, these vehicles look great if you want to use them to pull tree stumps. Unfortunately most of us use vehicles for commuting to work. At 18/24 mpg these vehicles really do nothing for overconsumption of oil in the US. I am glad the air will be clean though. Perhaps you only need 100 - 120 hp and 200 - 300 ft-lbs of torque instead of the 210/540 provided by this V6.
Posted by: | Mar 14, 2008 8:29:01 AM
I don't understand the point in using Diesel engines for these vehicles. The benchmark mpg figures seem low to me. What figures would an equivalent petrol (gas) vehicle acheive?
Posted by: Tim | Mar 14, 2008 8:30:46 AM
For clarification the 540 Nm of torque translates into 399 ft-lbs of torque. So 105hp/200 ft-lbs (105 hp/270 Nm) would be about 1/2 the power of this current engine. This should be enough to power this SUV from 0 - 60 mph in around 10 sec. and get about 30+ mpg. For family hauling it's simply not necessary to have so much power in an SUV.
Posted by: | Mar 14, 2008 8:42:34 AM
I presume they are starting out with hi specification vehicles because of the cost. Perhaps they will introduce 4 cylinder 2L engines later on, when they get the hang of the technology.
For reference, Nissan have a baby SUV with a 1.5L Renault diesel engine which is selling well in Ireland.
It is very good in supermarket car parks and over speed bumps. In fact, it is suitable for 99% of what people do.
(Nissan Quashqai). [ But it wouldn't be 50 state legal ]
Posted by: mahonj | Mar 14, 2008 8:50:39 AM
Rafael,
I think the E-Class picture is accurate. In this system the NOx trap produces ammonia that is used downstream by the SCR catalyst, eliminating the need for Urea injection to provide the ammonia.
This same system is used in Dodge pickup trucks with Cummins diesel engines. Cummins as also announced that this is one of three different systems that they will use to meet EPA10 regulations for commercial vehicles.
Eaton is also pushing this system for commercial vehicles.
BTW - I really enjoy reading your posts here at GCC
GSP
Posted by: GSP | Mar 14, 2008 9:22:37 AM
@ Tim -
according to Mercedes' German web site, the E320 CDI emits ~200gCO2/km in the NEDC. The comparable E350 gasoline model emits ~240, some 20% more - in spite of the higher C/H ratio of diesel fuel.
In fuel volume terms, the E320 CDI comes in at ~7.5L/100km (diesel), whereas the E350 requires ~10L/100km (premium gasoline). Both have the same tank volume, so the diesel gets 33% more range.
In the US, diesel has historically not cost more than premium gasoline but the combination of global demand and the introduction of ULSD have changed that. Diesel is typically fairly expensive in cold winters, because a fair number of US homes still rely on heating oil. Gasoline is more expensive in the summer driving season. In the long run, it's still reasonable to assume the relative premium for diesel will be no more than the ~12% greater energy content would suggest is fair.
http://www.eia.doe.gov/emeu/aer/txt/ptb0524.html
Fuel cost per mile will still be 10-15% lower than with the gasoline engine. You'd find much the same for the MPV and the SUVs, but their fuel consumption is higher in absolute terms.
Diesel therefore makes sense in the US for large, heavy passenger vehicles because the engine runs lean and quietly in freeway cruising, provided you rack up enough miles to amortize the up-front premium.
Small diesels - below ~2.5L - offer smaller TCO advantages in the US market, because meeting T2B5 emissions regs is so expensive.
@ GSP -
I see. That's a seriously expensive setup.
Posted by: Rafael Seidl | Mar 14, 2008 10:34:03 AM
This is a preview of what will be the ubiquitous diesels of tomorrow from all manufacturers.
Dodge Cummins powered deisel trucks already have had this setup from the 2007 model year. Chrysler, Ford, and GM have shown poorly disguised future vehicles as "concept vehicles".
Once again too bad the EU Greens are all talk and no action. I consider it significant that MB has said this is an America only setup. Let its EU and German citizens breathe filth, with the implicit compliance of the all-talk Greens.
Posted by: Stan Peterson | Mar 14, 2008 11:02:06 AM
If you had one with half the horsepower and torque that got 1-2 mpg more around town, people in the U.S. would still pick the more powerful model I bet.
Posted by: sjc | Mar 14, 2008 11:06:03 AM
Rafael, so using your numbers, the diesel is about 33% more efficient than the gas version, but how much dirtier is it?
At only 10-15% cheaper per mile, I'd have to think that a gas-hybrid would cost about the same, be vastly cleaner and easily reduce cost per mile by 10-15%, if not more (could probably get away with regular octane fuel instead of premium and save another 5-10% per mile).
City fuel economy would likely be significantly better with a hybrid, especially in slow traffic where the engine would be able to shut off frequently. (Although arguably it probably wouldn't take much to add start/stop functionality to the diesel).
Posted by: Dave | Mar 14, 2008 11:42:05 AM
The small displacement turbo FFV series/parallel hybrid looks good to me. If I could run a Honda Civic hybrid with a more powerful motor and a turbo on that 1.3l and get 150 hp and 100kw of power from high octane E85, it would get some pretty good economy. Run it dual fueled on NG and save even more.
Posted by: sjc | Mar 14, 2008 11:57:59 AM
@ Dave -
the point of emissions regs is to establish a threshold of "clean enough". EPA requires manufacturers to achieve T2B5 for their sales-weighted fleet average. California LEV II is numerically equivalent to T2B5 but set as the maximum per vehicle, rather than a fleet average.
These new Mercedes diesels are "clean enough" for both EPA and CARB. That means they are 90-99% cleaner (depending on component) than their forebears of the 1980s. It is no longer appropriate to reflexively label any and all diesels as dirty, even if it is possible to achieve even lower toxic emissions with gasoline engines. At current oil prices, it's time to stop disregarding the impact of emissions regs on fuel economy.
That said, if what you're looking for is a mid-sized or smaller car with modest performance and, you rack up a lot of miles in urban areas and traffic jams, an electric hybrid may well be the better choice. Diesels are only more economical than single-mode full hybrids at speeds above ~30mph.
Posted by: Rafael Seidl | Mar 14, 2008 12:13:12 PM
US Average gasoline prices now $3.28. Diesel $3.98. That is 15% more, just about what you might save in fuel economy.
Posted by: Joe | Mar 14, 2008 6:13:20 PM
Such a great car. BMW goes to diesel again. I wonder if the cost is getter higher than the past car they launch. Anyway I like it. Sounds good to me. Thanks BMW!!!
Posted by: auto body parts | Mar 14, 2008 6:31:10 PM
In my neighborhood, diesel is $4.29/gal, while regular is $3.25! Considering that, the higher up-front cost of these diesels, and the crappy mileage they are reporting, it does not look like a very good deal. But then MB customers don't really care about money, only the three-pointed star.
Posted by: George | Mar 14, 2008 11:28:54 PM
@Joe -
no, if you use 25-30% fewer gallons and each gallon costs 15% more, you're still ahead 10-15% in fuel cost per mile. A hybrid gasoline vehicle with comparable performance that gets 10-15% better mileage will result in the same fuel cost per mile, so it's worth sharpening your pencil. In Europe, differential fuel taxes greatly favor diesels and in some countries, CNG. In the US, consumers have a different choice of technologies.
Note that basing such computations on a spot price at any given time of year is fairly meaningless - you need to look at annual averages.
Posted by: Rafael Seidl | Mar 15, 2008 2:25:14 AM
Vielen Dank Rafael,
it seems from the various posts that that the T2B5 compliant diesel offers only modest fuel cost savings, but will offer some CO2 per mile reductions.
I don't know much about the reliability of large displacement detuned use gasoline engines, but in europe it is a common expectation for a diesel engine to provide many more miles in its life, so that may be a selling point for the high-mileage duty hinted at by Mr. Seidl.
I can't disagree enough with my favourite irritant Stan P, however. In Europe, there is more political emphasis on getting CO2 per mile, or even per family, down. If you look at average population density - the germans are alot closer to the tailpipe, but they drive less, produce less exhaust gas per capita and also breath more (they do a lot of excercise), than their american counterparts.
It would be interesting to compare the air quality figures for let's say Main/Ruhr areas and New York City.
http://www.env-it.de/umweltbundesamt/luftdaten/index.html
http://www.epa.gov/air/data/geosel.html
I see regional highest averages of >40 microgram/cubic metre in Germany and 0.034 ppm in Manhattan. Using density of air as 1.2kg/m3, I get 0.034 ppm = around 40.8 microgram/m3.
So the levels are quite similar at the moment - even though in the german cities, a high percentage of the vehicles are Euro 4 diesel or worse.
Posted by: Tim | Mar 15, 2008 4:25:52 AM
@ Rafael
Unfortunately Diesel continues to sky rocket and is now selling for roughly a 25-27% premium in my area(San Antonio). I am looking at replacing my vehicle in 1-2 years and was seriously considering a diesel, but am now concerned that will not be viable. Luckily I have plenty of time to see how this turns out, and hopefully diesel will soon return to more of a parity with gasoline.
Posted by: dsl987 | Mar 15, 2008 6:38:11 AM
Since the Diesel cycle is more efficient than the Otto cycle, maybe it is the fuel that is the problem. We now have low sulfur diesel, but that raised the cost and you still have particulates. I am not an expert, but I thought that diesels could run on CNG, if started with DME or some other fluid. So, convert the diesels to run on CNG or ANG and provide a small tank of starting liquid. They would run much cleaner and cost less to operate. Maybe the refineries need to get rid of the diesel much like they needed to get rid of gasoline after making kerosene, I do not know. But, it seems like these problems can be solved with some thought.
Posted by: sjc | Mar 15, 2008 11:17:34 AM
Sweet diesels. I would trade all that emissions bull crap for 1 extra hp. Burn baby burn!
Posted by: diesel | Mar 15, 2008 3:25:02 PM
I think it's possible that Mercedes-Benz could look at the possibility of licensing the plasma gas reactor technology developed by Honda as a means to generate ammonia gas to reduce NOx emissions on their smaller engines without lugging around a tank of AdBlue urea fluid. That could open the door for M-B to offer their 2.2-liter I-4 turbodiesel engine on the C220CDI model even here in the USA, which would significantly help the CAFE of the entire M-B line.
Posted by: Raymond | Mar 15, 2008 3:29:02 PM
Just curious...I have a 1979 240D why do I get 35-40 mpg and these new MB get such terrible fuel economy. I had a 79 VW Rabbit that got 66-70 mpg. The technology is 30 years old why is it so hard to have the emission controls and not have economy as well? I look forward to getting your input. thanks
Posted by: Richard | Mar 18, 2008 11:40:38 AM
Sorry Richard, but your 1979 240d does not get 35 -40mpg. I have one too, same year same model, and its mint, and it gets 25mpg. So I think your numbers are a little high. Lets be honest here.
Posted by: bosyphyllus | Jul 24, 2008 6:02:04 PM
