Featured BMW May Be Next For A Diesel Emissions Scandal

who here is surprised?

 

I've also read the BMW response which makes some sense:

The allegation brought a furious denial from BMW. For starters, it claims that 3000 rpm is a “very high engine speed” induced by operating the car in lower than normal gears and for short periods of times. The company claims that longer test segments using proper gearing would produce emissions results consistent with published specifications. 3000 rpm may not seem like much to most drivers (who know what that means), but diesels are known for low-end torque, not high-speed performance.​

We'll have to watch what the regulators say but IMHO a high-power transient, one much greater than normal operating range, could be a problem for all engine powered vehicles. I'm not in the market for a diesel but remember that it was a BMW diesel that showed they can meet emissions in normal road operation compared to the VW cheating diesels.

Cold-start is a high emissions region until the catalytic converter heats up. In like fashion, very high gas flow through a catalytic converter could easily exceed the ability to treat all exhaust products. This sounds like an edge condition, a small fraction of normal operation.

Bob Wilson

 

Understand that I am not a diesel advocate except perhaps as a range extender in a plug-in hybrid. Until then, BMW plans to address what is going on aggressively:
http://wardsauto.com/bmw-rejects-allegations-excessive-emissions

BERLIN, Dec 5 (Reuters) - BMW has denied that engine management software shut off a system filtering nitrogen oxides (NOx) emissions in some of its diesel cars after a German environmental group alleged that a 3-Series estate car in a series of road tests emitted amounts of NOx which were seven times above the legal limit.

The 2-litre, 320d car, which is designed to meet the latest Euro 6 standards on emissions, exceeded the statutory cap of 80 milligrammes of NOx per kilometre by an average of 2.6 times in eight road tests and even by 7.2 times when the car's speed was increased by 10 percent, Deutsche Umwelthilfe (DUH) said on Tuesday.

However, in a separate set of static roller-bed tests also conducted by the DUH in October, the results of which were not independently verified, the same BMW car's NOx emissions remained significantly below the 80 milligrammes per kilometre limit at normal speeds and when the speed was increased by 10 percent, the group said.

"The results give very clear signs of unlawful defeat devices in the engine control software," DUH managing director Juergen Resch told a news conference. "The vehicle must provide for fully functional exhaust gas cleaning in all normal operating situations."

The DUH's findings were reported by German broadcaster ZDF's programme WISO and daily newspaper Tagesspiegel on Monday evening.
. . . ​

Full disclosure, we own a BMW i3-REx, plug-in hybrid. The engine thermal efficiency is lower than it should or could be but adequate for the rare, highway trip. IMHO, a range extender engine should operate at peak efficiency point with a well managed emissions. Replacing the gas engine with a BMW diesel would not cause me to 'set my hair on fire.'

Bob Wilson

 

I was disturbed to read the light details in the news reports. Here is something with meat including the comments:
Green Car Congress: DUH says testing indicates use of defeat device in BMW 320d diesel

Bob Wilson

 

I'm having trouble getting past their acronym.

Second on checking out the comments.
I'll add that the NEDC tests the DUH is using as their multiplier reference is at low speeds and light loads. Gasoline cars that pass it will regularly exceed the emission limits when tested on the road.

 

Excess NOx emissions have also been reported in the BMW 520d under aggressive driving. In a blog post, the ICCT says: (Will the future RDE regulation be enough to restore trust in diesel technology? | International Council on Clean Transportation)

A deeper investigation also revealed a measurable discrepancy in the behavior of the lean NOX trap (LNT) aftertreatment system (i.e., how the emissions are treated once they leave the engine) in the BMW 520d, whose NOX purges were never triggered under more dynamic conditions. It is as if the vehicle had no NOXaftertreatment, similar to a Euro 5 generation vehicle at best.
​

Even if these "occasional" non-conformances are unavoidable with diesel engines, they still need to be considered when diesel cars are compared to hybrids. Diesels can be made to have low-emissions, but it seems it is not easy.

 

This is the challenge. Sure a Dodge Viper can pass the emissions test by following the EPA drive protocol. But there is no emissions testing at maximum performance where the gas flow could be orders of magnitude greater and higher temperatures. In fact it would make sense to bypass a catalytic converter to preserve EPA operating range performance and not blow its guts out.

Absent detailed technical information and the opportunity to do my own testing, I'm just someone reading the news. But right now, there isn't enough to say this is a 'cheat device.'

Bob Wilson

 

Reading the comments, my guess is BMW is not "cheating". Software controlling EGR isn't a device, even though the euro regulators like to say it is. The question is whether this software map is illegal, my guess is it is not.

The whole euro 6 regulation is incredibly strange and full of possibilities to pollute much more in the real world than on the test. The US regulatory environment is better here, though possibly too strict ;-) The lab that caught vw in the US, did not have any similar problems with bmw in real world testing. Of course software in bmw cars is different in Europe than the US. It is highly possible that egr is reduced at high rpms to reduce soot clogging the particulate filter in europe. These filters do not do well if the cars rarely drive on the highway, and european driving cycle is quite different than the american one. I'll wait to see what the court says. Either way the bmw 330e or i3 seems like a much better choice for the american market than the 320d.

Compare Side-by-Side


The phev gets 14 mile electric then 30 mpg, the diesel 36 mpg, the normal 27 mpg. The diesel accelerates pretty much like a camry, the phev and regular bmw 330i much better beating it to 60 by more than a second, and sounding better while they do it. Emissions are much lower in the phev. fueleconomy.gov says the diesel will save you $500/year on fuel costs versus the phev, but I bet you pay that back in urea and maintenance of the diesel. After federal tax credit, even if there are no other state incentives, the phev is less expensive, better performing, lower polluting, than the diesel.

According to dashboard, year to date the phev 339e has sold 3778 to the diesel 328d's 1478, the i3 5604. I don't think we really need to worry about many people buying a bmw diesel in the US in the future. Europe? Maybe depending on regulations.

 

I haven't looked at the 330e, but I have done an emissions comparison of the 328d and the 330i.

"GreenerCars" rates the 2017 328d "greener" than the 330e:

2017 BMW 328D | Greener Cars

2017 BMW 330e | Greener Cars

 

I've got to say greener cars has systemic errors and their definition of green, is very different from my statement of lower pollutants. I don't want to go into the details, but they makes some pretty bad assumptions just based on weight about environmental costs of the cradle (building) and grave (throwing away and recycling) vehicles. The phev is 600 lbs heavier than the non-plugin gasoline car, and I'm sure much heavier than the diesel, which means greener cars thinks its not as green. The i3 because it uses carbon fiber is light, so greener cars thinks its green.

What I mean by lower polluting is unhealthy pollutants during use. Here both phev and diesel versions of the 3 series do fairly well in epa, nedc, and real world testing when it comes to particulates, carbon monoxide, and hydro carbons. Both epa and nedc underestimate NOx pollutants on diesels in the real world especially on short trips or cold weather. Even using the tests NOx is much lower well to wheels in the phev than the diesel, although the diesel still does well with its scr. On ghg well to wheel, not cradle to grave (which i admit is tough to predict based on lifespan, and recyling versus disposal, and maintenance), the phev is slightly better in the general US grid. It really comes down to use. With short trips the phev is much better. In several hundred mile highway trips the diesel will get in the good range of SCR and superior highway mileage will win for the diesel in terms of ghg. Lots of highway miles will also help the particulate filter be more effective.

 

Oh I completely agree about GreenerCars. I don't like their methodology either. I just don't have any other metric with which to compare at this time.

Since the VW TDI debacle, diesel vehicles certified in the U.S. are being subject to months of additional emissions testing (according to CARB: "driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use"). So even though there may be extreme off-cycle conditions that may cause higher exhaust NOx, the certified composite emissions should be relatively representative of the real-world emissions.

BMW in particular is using a combination of SCR and LNT (call passive NOx adsorber (PNA) in this case) on all of its diesel vehicles certified in the U.S. (since 2014). The PNA is effective in capturing most NOx during cold starts and/or conditions which cause the SCR to drop to less than optimum temperatures. The PNA releases the adsorbed NOx when exhaust temps significantly increase, at which time the SCR become highly effective. Of course, this is expensive, but it can be absorbed into the cost of more expensive vehicles like BMWs.

 

Something in this report confuses me:

Conventional Gasoline upstream VOC emissions...

3.035 grams (Petroleum Extraction & Transportation) + 3.162 grams (Total Petroleum Refining) + 42.91 grams (Fuel Transport, Storage, Distribution) = 49.107 grams VOC/mmBTU
. . .
Low Sulfur Diesel upstream VOC emissions...

3.035 grams (Petroleum Extraction & Transportation) + 3.063 grams (Total Petroleum Refining) + 1.261 grams (Fuel Transport, Storage, Distribution) = 7.359 grams VOC/mmBTU​

Almost a factor of 34 difference in the "(Fuel Transport, Storage, Distribution)" between gasoline and diesel seems a little high. I'm OK with the refining difference but the handling from refinery to the pump seems excessive.

FYI, I concur about Greener Car methodology in part because it tries to include the vehicle life-cycle costs. After the CNW Marketing fiasco, I'm a little jaundiced.

Bob Wilson

 

Those are EPA's data, but they seem reasonable to me. Gasoline is something like 500 times more volatile than diesel fuel at STP. So much higher VOC emissions during transport and storage don't appear to be out of line.

Please let me know if you find something different.

 

This makes sense but also suggests there may be opportunities to reduce it further. I was aware that the gasoline trucks had a vapor return line to capture what came out of the station tank. Just I wasn't aware the volatility difference was that great.

Thanks,
Bob Wilson

 

Bob - I know you're an engineer, so if you or any others on this site notice any errors in the 330i vs. 328d emission calculations, please let me know. That's my analysis, and I'd like any constructive criticism if you have any.

 

Ok, but you might not like my methodology:

	metric	2017 BMW 330e	2017 BMW 328d	comment
1	total range	350 mi	540 mi	fuel economy gov
2	EV range	14 mi	0	fuel economy gov
3	fuel range	336 mi	540 mi	calculated
4
5	EV rate	47 kWh/100 mi	0	fuel economy gov
6	fuel rate	3.3 gal/100 mi	2.8 gal/100 mi	fuel economy gov
7	$/kWh	$0.10	$0.10	local Huntsville electrical rate
8	$/gal	$2.48/gal	$2.47/gal	Gas Buddy search
9
10	EV $ one charge	$0.66	$0.000	calculated corrected!
11	fuel 336 mi	11.09 gal	9.41 gal	calculated for BMW 330e fuel range
12	$fuel 336 mi	$27.50	$23.24	calculated fuel cost 330e fuel range
13	$total 350 mi	$28.16	$24.21	calculate cost 330e range

• Within the range of the BMW 330e, the BMW 328d is more affordable

So now the problem is what is the break even range where the cost of the BMW 330e equals the cost of the BMW 328d:

	miles	2017 BMW 330e	2017 BMW 328d	comment
1	0 mi	$8.18/100 mi	$6.92/100 mi	fuel cost per 100 miles
2	0 mi	$1.26/100 mi	$0.00/100 mi	extra fuel cost of BMW 330e
3	14 mi	$0.66	$0.969	EV range cost of BMW
4	14 mi	$0.000	$0.26	BMW 328d extra cost
5	20 mi	$1.64	$1.38	fuel cost for each to travel 20 mi
6	34 mi	$2.30	$2.35	cost of BMW 330e and BMW 328d

• Within a daily travel of 34 miles, the BMW 330e and BMW 328d are equal cost
• Shorter than 34 miles/day, the BMW 330e is the more affordable ride
• Longer than 34 miles/day, the BMW 328d is the more affordable ride

Does that help?

Correction: After waking up from a nap, I noticed failure to calculate the electrical cost for 14 miles with the BMW 330e. With the right cost, the two cars have a much shorter, break-even range. My bad @wxman.

Bob Wilson