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DaimlerChrysler Hopes BLUETEC Initiative Will Catalyze Light-Duty Diesel in US

The basic BLUETEC system process. The order may vary based on implementation.

The introduction of the E320 BLUETEC in the US this fall (earlier post) marks the beginning of a worldwide initiative by DaimlerChrysler’s Mercedes-Benz group to offer a range of diesel vehicles that comply with the strictest emissions standards anywhere in the world—including all 50 states in the US.

To achieve that goal, the vehicles must meet the EPA’s Tier 2 Bin 5 requirement, which maps (deliberately) to the baseline California LEV II LEV requirements (adhered to by California and those states that have opted for the LEV regimen).

The two areas of major difference between the less stringent EPA Tier 2 Bin 8 (which becomes the uppermost level permissible at the end of 2006) and Bin 5 are in NOx and PM emissions. Getting from Bin 8 to Bin 5 (and CA LEV compliance) requires a 64% further reduction in NOx and a 50% further reduction in PM emissions.

US EPA Tier 2 and CA LEV II Standards (g/mi)
Category 50,000 miles 120,000 miles
EPA Bin 8 0.14 0.02 3.4 0.015 0.20 0.02 4.2 0.018
EPA Bin 5 0.05 0.01 3.4 0.015 0.07 0.01 4.2 0.018
CA LEV 0.05 0.01 3.4 0.015 0.07 0.01 4.2 0.018
CA ULEV 0.05 0.01 1.7 0.008 0.07 0.01 2.1 0.011

The ever-tightening requirements on multiple criteria have pushed automakers to explore a range of different systems and solutions.

BLUETEC is both an umbrella term that includes different emissions aftertreatment technologies and applications of technologies to solve the basic problem of emissions reduction as well as a descriptor applied to the various solutions of reducing oxides of nitrogen underneath the larger BLUETEC banner.

The design of each BLUETEC system depends upon the operating characteristics which must be considered in achieving the Bin 5/LEV target required for 50-state sales.

Each BLUETEC system performs the same combination of processes:

  1. Reduce carbon monoxide (CO) and hydrocarbons (HC). This is currently done with oxidizing catalytic converters (Diesel Oxidation Catalysts—DOC).

  2. Reduce particulate matter (PM) with a particulate filter, either as a separate element or integrated with one of the other BLUETEC elements.

  3. Reduce NOx. This is a problematic area for all manufacturers, and one in which Mercedes is opting for two approaches. The first is a newly developed NOx adsorber, a catalytic device that converts NOx to nitrogen. The other is a urea-based injection system (using an aqueous urea solution called AdBlue, the genesis of the BLUETEC name). Both are combined with Selective Catalytic Reduction systems, which, while in principle are the same, differ in application design based on vehicle parameters and emissions targets.

These operate in conjunction with in-engine reduction of emissions via improved engine management, enhanced high-pressure common-rail fuel injection systems, and turbocharging with exhaust gas recirculation.

Bluetec2 Glbluetec
E320 BLUETEC Emissions System with DeNOx catalyst. VISION GL320 BLUETEC Emissions System with AdBlue injection system.
Click each diagram to enlarge.

For the E320, due to be released in the US later this year, DaimlerChrysler implemented the DeNOx adsorber. The EPA tested an earlier prototype of this car, along with light-duty diesels from several other manufacturers, between April 2002 and October 2003 (results reported in the SAE paper referenced below).

The testing results of the prototype E320 show the early capabilities of the system, and also highlight advances DaimlerChrysler engineers have made over the last few years in fuel efficiency while maintaining emissions control. During the test process, the E320 delivered about 31 mpg—as announced, the E320 BLUETEC promises 35 mpg.

The system on the concept VISION GL BLUETEC full-size SUV, which is the same as applied on the concept Jeep BLUETEC, uses the AdBlue injection system for more robust NOx reduction. Without the AdBlue system, Mercedes would have only complied with Bin 8, according to Prof. Herbert Kohler, Head of the Vehicle Body and Drive Systems Directorate and DaimlerChrysler Environmental Officer. In other words, it wouldn’t have met the 50-state goal.

The urea-based selective catalytic reduction systems, in which the injection of the AdBlue urea solution into the pre-cleaned exhaust gas releases ammonia (NH3), causing the nitrogen oxides to be converted into nitrogen (and water) in a downstream catalytic converter, is currently the most effective established aftertreatment technique for NOx reduction, and is looked to by many truck manufacturers as the solution for their commercial diesels.

The problem with these systems, according to some—notably the EPA itself—is the requirement to replenish the tank of the aqueous urea solution. No AdBlue, no NOx reduction.

DaimlerChrysler has been lobbying the EPA for several years to change the agency’s mind on the use of urea injection systems.

The AdBlue tank (normally hidden with a liftable cover) in the Jeep BLUETEC concept.

The company counters that since an average of around 0.1 liters per 100 km (2,352.15 mpg of AdBlue or 1 to 3 percent of diesel consumption) is all that is required, the tank can be designed so that it only needs to be refilled when service staff are carrying out regular, scheduled maintenance. In other words, take it out of the hands of the drivers.

The company has a large base of operating experience from which to speak on this area, having delivered more than 10,000 AdBlue-based commercial diesel vehicles in Europe over the past number of years.

Outlook for diesel. DaimlerChrysler is becoming increasingly bullish about the prospects for diesel in the US, given the rising concerns about fuel economy here combined with apparently ongoing customer demand for size and performance.

J.D. Power and Associates forecasts that the market share for diesel passenger cars in the US, which currently stands at around 3.4%, will quadruple by the year 2015. Mercedes-Benz is convinced that once BLUETEC technology has established itself, this forecast will appear conservative rather than optimistic.

Accordingly, the Mercedes group will share the technology with the Chrysler group, as evidence by the Jeep prototype. The pace of that, and the pace of the overall BLUETEC diesel rollout in the US, will depend to a great extent on the customer reaction to the E320s when they hit showrooms in the fall.

This may, over the next several years, contribute to altering the competitive landscape for improved fuel-efficiency, with clean diesel cars becoming poised to occupy the territory currently being scoped out by many hybrid implementations—fuel economy improvements of some 20–30% over comparable current gasoline platforms—with a lower-cost solution than hybrids.

Mercedes’s GL BLUETEC full-size SUV, for example, is projected to offer fuel economy of 26 mpg US; the upcoming Chevy Tahoe Hybrid 25 mpg.

The diesels are simpler, more reliable [than hybrids]. I can say this as someone who is on both sides of the position.

—Prof. Herbert Kohler, (referring to DaimlerChrysler’s ongoing hybrid powertrain development with GM and BMW)

In 2004, Margo Oge, Head of the Office of Transportation and Air Quality at the US Environmental Protection Agency (EPA) noted that:

If we had a light duty vehicle population that was one third diesels, that could save up to 1.4 million barrels of oil per day in the US, the amount of oil the US currently imports from Saudi Arabia. If we made these vehicles diesel hybrids, the oil savings would about double or up to 2 times the amount of oil Saudi Arabia ships to the US every day.

DaimlerChrysler appears very interested in developing that combination (diesel hybrids)—assuming it sees the demand with its BLUETEC vehicles.




Wow. Very interesting article. Thanks for posting this. It seems like the EPA is overly zealous about NOx reduction why completely ignoring the elephant in the room: CO2!


EPA could also consider other ways to mitigate the NOx problem rather than ruling out auto technologies that help with CO2. Just as companies now offset CO2 emissions by planting trees, why not consider Titanium Dioxide as a catalyst away from autos as is being tried in some other countries.

Jack Rosebro

The reason that the EPA is skeptical of AdBlue technology is that AdBlue-equipped vehicles can be driven after the AdBlue solution is used up, thereby increasing the vehicle's emissions. DaimlerChrysler could modify the vehicle to simply shut down when the AdBlue solution runs out, but somehow, I don't think DCX will be interested in that solution.

My experience with emissions programs is that any emissions technology which can be defeated by the vehicle operator will be promptly bypassed. An illuminated service warning light won't be enough to make American consumers fill up with the stuff when it runs out.

I am hoping that a compromise can be worked out, as I admire the technology, but in this case, I think the EPA's concerns about AdBlue in the real world are justified.


I'm still amazed at the tight, future restrictions required by the EPA in regards to NOx. If you look at Tier 2, Bin 5; the CO level is extremely relaxed (3.4 g/per mile)as compared to .05 g/per mile for NOx. PM I can understand due to all the evidence that points to this emission as being a carcingen; but this regulation seems so anti-diesel in nature since it allows such relative high levels of CO, which is an emission more associated with gasoline-powered vehicles, while being very tough on the two emissions most associated with diesel-powered vehicles.

If the EPA suddenly decided to restrict CO levels below 1.0 g/per mile, it would be gasser technology that would be struggling for viability instead of superior diesel technology. I would think that CO is at least as damaging to the environment as NOx, and I believe studies such as the "Weekend Effect" help to proove my point.

I just can't believe that diesel technology is having to go to such extremes when they have cleaned up emissions by 90% since 1985; have solved all emission issues except for NOx; and are reducing NOx by around 25% per year w/o the use of adsorbers or urea injection systems.

With all the advantages that diesel power could bring to our light-duty market, including reducing energy dependency, I would think that our EPA could allow diesel technology a relaxed standard on NOx and allow a gradual movement towards the gasoline standard without all this "BlueTec" stuff.


Spot on comments greg. Absolutely dead on the money. A tradgedy really, this situation - American's ignorance of this tech, and their haste to attack it, really disgusts me.


For the most part folks have learned that if your car runs out of fuel it will stop running. Why couldn’t they deal with: if it runs out of fuel it will only go 40MPH till you fill it back up. Sure beats walking to the next exit.


The Bluetec program includes more than just the Urea injection system to reduce NOx. How about using the Delphi NOx reformulator shown in the side bar, in conjunction with the Urea system? A "limp-home" mode would be a good alternative when it runs out of Blue-Juice, provided it is widely available at Mega-Marts and auto-suppliers.

Charles Foschini

I heard & have read that diesel causes tremendous problems for those with allergies and asthma. Is this particulate emmissions related? Is it stopped by the new emmission standards, which makes it cleaner than gas except for the CO2 production (not a known allergy causer from what I have read) ?

brian kelly

The US needs to reduce dependence on foreign oil. Here is a ready solution for a wide range of vehicles in the form of Bluetec. SO... the challenge of how to make sure the adblue tank is filled up seems trivial compared to the challenges of other oil saving technologies such as fuel cells and even E85.
This is one is ready to go and makes good sense. Hey I am even buying some DCX on the strength of this!

Don Brousseau

I'd buy a Bluetec Jeep Unlimited Rubicon in a minute ! Oops. Before I commit, does anyone know an approx. predicted price for such an engine option? Better fuel economy and greener emissions are long overdue. We try to buy American, but as time goes on, foreign auto maufacturers continue to outpace us in these areas. Maybe Bluetec will be the start of a better future. If these motors are as good as predicted, they could help the American consumers come up for ( a breath of fresh ) air.

Bill MacQuoid

I saw a motorhome with a bumper sticker that read "OPEC can suck my exhaust" 100% Soy Biodiesel. With all the subsidies dealt out to midwestern farmers to "not" plant their fields, it would only seem to make sense to have them plant Soy Beans and boost this "Clean" diesel alternative for everyone's benefit. One station in Phoenix here sells this for $2.95 a gallon.


Thanks for the great SAE paper.


There is much doubt or i should say limited knowledge about this subject to yet fully appreciate the eventual impact of lowering greenhouse emissions. We as a society should and i believe,embrace these new concepts and in turn lower costs for the consumers which in turn is at least a start in right direction to helping our home, our PLANET.


the range of AdBlu being set to match service periods would remove the need for an "add adblu" light because a service vehicle soon light would get most cars into a service shop to refill tank + dealer mailouts / reminders
+ if aircare type testing is required they could check the tank level.
the operator doesn't need to even know about the stuff

I cant wait to drive a good that runs on economy. How many kilometres to a litre does it run on. Everything else seem good

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