TDI NOx emissions compared to average car

[DRotblatt]

I just purchased a Golf Sportswagen TDI August 30...two weeks later the news hit. Seemed really bad, but I really wanted to know: "Just how much pollution is my TDI putting out compared to regular gas cars on the road?"

Let me know if my thinking seems right, because the news isn't good.

Searched all over the web and finally found the EPA test results for cars tested in each year. The document for year 2015 "Certified Vehicle Test Result Report Data (XLS)" in http://www3.epa.gov/otaq/crttst.htm shows those results. Here are some random examples (I just found 4 cars I recognized), along with the Jetta TDI:

Ford Explorer: NOx=0.01300, CO=1.67000
Mini Cooper (5 Doors): NOx=0.01550, CO=0.39000
Dodge Dart: NOx=0.02000, CO=0.85000
Jeep Cherokee: NOx=0.01300, CO=1.39000
Jetta (gas): NOx=0.0149, CO=0.3770

Jetta (diesel): NOx=0.03100, CO=0.0100

The Dodge dart is the worst offender, with a NOx of 0.02000 g/mile. Thus if my TDI is doing 15X the max emissions (.05), then it is equivalent to 37.5 Dodge Darts on the road. If we compare it to the best (the jeep or explorer???) it's like 57 jeeps/explorers of NOx emissions.

It is like my worst nightmare...

[imurrx]

I think TDI vastly outnumber Darts.

[ChemMan]

The fleet average (often call "max emission" or "legal limit") is 0.07 g/mi. This is the same as Tier2Bin5 full lifespan (10 year 120K miles) limit. Using zero prefixed decimal places drives me crazy so I will write everything in mg/mi. The vehicles in your list range from 13 mg/mi to 20 mg/mi. The max fleet average is 70 mg/mi (Tier2Bin5) and the absolute limit per vehicle is 200 mg/mi (Tier2Bin8). In the WVU study the Jetta was tested on 8 road tests involving urban, rural, and hwy conditions. The emissions ranged from 614 mg/mi to 1480 mg/mi. Across all 8 road tests the mileage weighted average would be 1084 mg/mi.

Understand however that only three vehicles were tested in the WVU study, a 2012 Jetta, a 2013 Passat, and a 2012 BMW X5. The WVU study blew the whistle and subsequently the EPA widened the investigation to in include your Golf but we don't know what the emissions of the Golf are. The EPA hasn't released the details of their findings (and they won't as this is an ongoing investigation).

Still you shouldn't really compare diesel vehicles to gas vehicles and look at only NOx. Gas vehicles generally don't have any significant NOx emissions. They tend to operate at a lower temp which means less NOx production and then they have the highly efficient 3-way cat (>99% reduction in NOx). On the other hand gas vehicles tend to have more CO and more unburned hydrocarbons (NMOG). Diesel vehicles tend to have more NOx and more PM (particulate). So for a more apples to apples comparison I would compare it to other diesel vehicles.

Lastly CO2 is directly related to fuel consumption. When comparing between two fuels keep in mind that 1 gallon of diesel has 13% more carbon. So 40 mpg gas ~= 45 mpg diesel in terms of CO2 output. As a side note the EPA mpg rating is calculated based on the weight of the CO2 which is emitted. If you run a vehicle and capture the exhaust and the CO2 in the exhaust weighs 10.15 kg then you have burned 1 gallon of diesel. Yes technically fuel isn't completely burned (NMOG, particulate, CO, HCHO, etc) so one should really measure and weigh all those and compute what portion came from the atmosphere. As a practical matter those non-CO2 outputs are a rounding error <0.1%. So the weight of the carbon in CO2 = weight of carbon in the fuel.

[ChemMan]

Also nice find. I had been looking for this for years. I hate using websites and would prefer the raw data.

[amstel78]

Now compare those findings against heavy duty vehicle emissions and you'll see that our TDI's are still very tame in comparison.

http://www3.epa.gov/otaq/consumer/420f08027.pdf

[DRotblatt]

ChemMan, thanks! I looked hard for a week before I happened on that data. I really wanted to know how the NOx from my car compared to others on the road (gas or diesel) and all I could find was mention of the .05 g/mile (or 50 mg/mile) MAXIMUM amount, not actual figures and no comparison with other cars. I didn't look at CO or HC because VW didn't lie about that...thus it falls under EPA amounts. The only figures for HC in the EPA data is; HC-NM+NOX, which is a calculation that includes NOx, thus would be invalid for the Jetta Diesel (the only VW diesel that was tested in 2015). Lastly, the actual figures for NOx for gas and diesel are not too much different since they all are trying to meet similar EPA standards. Here's some diesels:

Ram 1500: NOx=.024
BMW X3 xDrive 28d: NOx=.008
BMW 740Ld: NOx=.015 CO=.05

amstel: I hope that's tongue in cheek....but as it turns out, the figures from the data are much lower then your link indicates. According to EPA data, the Dodge Ram 3500 (first large pickup I found in the data...and it's a diesel) is putting out .17 g/mile NOx (but lots more carbon). I also found a Ram 3500 Promaster gas model (a van)...that was .03 g/mile NOx. That means at 15X I'd still be putting out the same as 3 Ram 3500's, or 25 giant Ram Promaster Vans. Not feeling the love here

[amstel78]

Originally Posted by DRotblatt

amstel: I hope that's tongue in cheek....but as it turns out, the figures from the data are much lower then your link indicates. According to EPA data, the Dodge Ram 3500 (first large pickup I found in the data...and it's a diesel) is putting out .17 g/mile NOx (but lots more carbon). I also found a Ram 3500 Promaster gas model (a van)...that was .03 g/mile NOx. That means at 15X I'd still be putting out the same as 3 Ram 3500's, or 25 giant Ram Promaster Vans. Not feeling the love here

No, not tongue in cheek. I intended to show a comparison between the data you found and the EPA averages for large commercial vehicles, such as 18-wheeled tractor trailers. FWIW, there are a whole lot more commercial diesels on the road in the USA than there are VW TDIs. For instance, the lowest weight category tested by the EPA (IIb or vehicles over 8500lbs) show an average NOx emission rate of 3.08g/mile. That is significant.

OTOH, the comparison you make between our cars and the newest Dodge RAMs with Cummins engines seem a bit unfair; those trucks have DPF units, NOx catalysts, and UREA injection systems. Out of curiosity though, I'd like to know what the emissions readings are from the same RAM 3500 towing a fully laden 18,000lb gooseneck. I'm fairly certain the NOx emissions won't be so low.

[crazyrunner33]

Originally Posted by amstel78

No, not tongue in cheek. I intended to show a comparison between the data you found and the EPA averages for large commercial vehicles, such as 18-wheeled tractor trailers. FWIW, there are a whole lot more commercial diesels on the road in the USA than there are VW TDIs. For instance, the lowest weight category tested by the EPA (IIb or vehicles over 8500lbs) show an average NOx emission rate of 3.08g/mile. That is significant.

OTOH, the comparison you make between our cars and the newest Dodge RAMs with Cummins engines seem a bit unfair; those trucks have DPF units, NOx catalysts, and UREA injection systems. Out of curiosity though, I'd like to know what the emissions readings are from the same RAM 3500 towing a fully laden 18,000lb gooseneck. I'm fairly certain the NOx emissions won't be so low.

Given my experiences from towing and driving an unloaded 2014 RAM with urea, I wouldn't be surprised if the NOx remained low. Thanks to the urea, EGR isn't used much when unloaded, the fuel economy matches or exceeds my '97. However, when towing it will drink the urea pretty heavily, around 3-5 gallons when towing a thousand miles. Plus, the fuel economy takes a huge hit when compared to the 12 valve towing the same trailer. I assume that EGR is being used more along with a reduction in timing and the high urea consumption to keep NOx in check. Again, these are assumptions, I'd like to see if there's data to back it up.

[DRotblatt]

Originally Posted by amstel78

OTOH, the comparison you make between our cars and the newest Dodge RAMs with Cummins engines seem a bit unfair; those trucks have DPF units, NOx catalysts, and UREA injection systems.

My interest is the pollution of my car...a brand new 2015 Sportswagen with the Urea injection system. Further, one of the cars in the West Virginia study was a Passat with Urea injection - and it failed miserably. Just because I'm putting out less NOx then a big rig or tractor does not make me feel better - I just can't use that rationalization.

[Jedadiah]

Your GSW has an EA 288 which wasn't tested by WVU. Both cars were EA 189. In Europe, the EA 288 aren't being recalled at all, just the older cars. At least WV is pretty sure your car meets The Euro standard.

More than 50% of cars in Germay are diesels and very many are EA 189 VW's. People aren't dying, choking to death on Nox in the streets. Our 1% diesel rate isn't really hurting anything.

[DRotblatt]

Originally Posted by Jedadiah

Your GSW has an EA 288 which wasn't tested by WVU. Both cars were EA 189. In Europe, the EA 288 aren't being recalled at all, just the older cars. At least WV is pretty sure your car meets The Euro standard.

I think that's the most optimistic scenario, and the one I'm hoping for. My hypothesis (in my optimistic moments) is that in 2013 VW knew the jig was up, and started developing the EA 288 to replace the EA 189 and phase out the fraudulent software...keeping it in the first year 2015 so if they needed to they could tweak the emissions with a software 'fix' if it didn't meet standards. In 2016 they left out the software.

To back this up, on the site vwdieselinfo.com they stated in the FAQ that they felt the MY2016 cars met EPA standard...but that verbiage has been dropped in the past day or so. Now they just say they are working with authorities to fix the problem. This leads me to believe that my best guess hypothesis may not be right. I hope you are correct about their meeting standards in Europe at least.

Originally Posted by Jedadiah

More than 50% of cars in Germay are diesels and very many are EA 189 VW's. People aren't dying, choking to death on Nox in the streets. Our 1% diesel rate isn't really hurting anything.

Dramatizing to make a point makes rationalization easy, but doesn't work for me, and isn't true. The slight increase in NOx will have a slight effect, but in a city of almost 20 million, that could be thousands of people that are effected with increased health ailments. I remember when the smog in this city was so bad the air looked like something out of a apocalyptic Sci Fi movie, we had to stay indoors on bad smog days. It's an increase in standards and regulations that have changed that...after all, corporations won't on their own (case in point VW), and from what I read on this forum neither will many individuals. I was tired of being part of the problem, and thought I would be doing less harm with this car.

[piotrsko]

you Are making a difference in driving your car. It IS more efficient, therefore less polluting by definition.

[RalphVa]

I wonder if anyone has taken a look at diesel's NOx total from crude to highway and COx vs. a gasoline engine's. I'll bet diesel still takes a lot less refining than gasoline.

Ralph

[wxman]

Originally Posted by RalphVa

I wonder if anyone has taken a look at diesel's NOx total from crude to highway and COx vs. a gasoline engine's. I'll bet diesel still takes a lot less refining than gasoline.
Ralph

The upstream emissions of gasoline is nearly twice as much as diesel with respect to NMOG/VOC+NOx.





Of course, the vehicle operations emissions are now much higher for the tdi, but the upstream emissions are much lower.

[donallen]

Originally Posted by piotrsko

you Are making a difference in driving your car. It IS more efficient, therefore less polluting by definition.

No, not "less polluting by definition". There are a variety of pollutants. NOx is one, CO2 is another. They both do harm in different ways. The TDI was sold to us as having low rates of emissions of both. The CO2 story was true, because CO2 emissions are inversely proportional to fuel efficiency. But the NOx story was grossly fraudulent. The TDIs emit far too much NOx pollution on the road. Despite the EPA bashers on these forums, there's a damned good reason for the emissions standards in this country. They were designed by medical people who know what they are doing and know the research, unlike the know-nothings posting here.