Diesel Prius

I saw it earlier but some of it did not make a lot of sense until I found the Federal Standard. Now I understand how easy it is to get different numbers depending upon how the vehicle is rated, TLEV, LEV, or ULEV. But going back to Non-Methane Organic (NMOG), notice it is about 1/3d to 1/5th the rate of the NOx (50k Intermediate):

• <category> - NOx / NMOG
  
• TLEV - 0.4 / 0.125 = 3.2
  
• LEV - 0.2 / 0.075 = 2.7
  
• ULEV - 0.2 / 0.040 = 5.0

What this means is we can use NOx as a first approximation in most cases for the effective rates of pollution. BTW, the pressurized tank of the BMW i3-REx has no NMOG so it is NOx or nothin'.

I don't care for the XLS data format because it is terribly hard to lookup and sort 'like-to-like' test results. But I think I can reformat it to be like the CSV style so each row is one vehicle and one test with all of the data metrics in identical columns. This will make it a lot easier to compare vehicles even if NMOG+NOx is treated as the 'gold standard.' And then along comes my BMW i3-REx. <grins>

As you pointed out, there is a transition going on and there are partial fractions used to calculate the fleet average of a manufacturer and a schedule over time. But this has more to do with fines or busting CAFE and not 'technical bragging' rights.

What really got me was how high the absolute NOx rates are, 0.2-0.4 gm/mi. Until I checked the standard, I thought it was 0.060 gm/mi. So we're looking at already some numbers that are friggin' great when expressed as a percentage. I maintain that if one car is at 3% and other at 5% of the limit, they are close enough to be identical. No, I'm not trying to use percentages to make a 'silk purse.' Rather trying to keep things in perspective:

During the 1940s when the Soviets were developing their first atomic weapon, the man in charge of purifying uranium bragged that he had achieved 'a higher ratio of U-232 than the Americans.' Then the scientist-prisoner pointed out the Americans only purified it enough to make a bomb and no more.​

Bob Wilson

 

The thing of it is is that NMOG and NOx are combined into one standard for both Tier 3 and LEV3.

I'm not sure if EPA will continue to break out NMOG and NOx separately in the test car data.

 

The emission standards are really beside the point anyway. My comments in Post #149 were to disagree with a previous comment that light-duty diesel vehicles can barely meet the weakest emission standards currently in effect. That's demonstrably not true, I used the 2017 BMW 328d actual certified emissions as support. The certified emissions of the 328d are all well below the ULEV standards.

It wasn't really to claim that the 328d has the lowest emissions of any 2017 model year vehicle, or has the "bragging rights" for such. I acknowledge that I haven't check every cert in CARB's 2017 executive orders file. I just haven't yet run across any certified "composite" NMOG+NOx emissions that are lower (except for the 2017 Volt, but the evaporative VOC emissions push that metric above that of the 328d's). Again, the "composite" emissions are a weighted average of the emissions from the FTP, US06 and SC03 test duty cycles (weighted at 35%/28%/37%, respectively).

 

I used the XLS file and reduced the vertical metrics to columns on each row for each car under each unique test:
https://drive.google.com/open?id=0B6ME0cciJ0tobmd3QlMxNkpGaWs

	NMOG+NOX	Represented Test Veh Make	Represented Test Veh Model	TEST_NUMBER
1	0.0000	Aston Martin	V12 Vantage S	FASX10028339
2	0.0000	KIA	Soul ECO dynamics	EKMX91001840
3	0.0000	KIA	Soul ECO dynamics	EKMX91001841
4	0.0000	BMW	I3 REX	HBMX10042302
5	0.0000	BMW	I8	EBMX10032484
6	0.0003	BMW	328d xDrive Sports Wagon	GBMX10036460
7	0.0003	Ford	Fusion (PHEV)	HFMX10040129
8	0.0003	HYUNDAI	SONATA HYBRID	GHYX10033919
9	0.0003	HYUNDAI	SONATA PLUG-IN HYBRID	GHYX10036007
10	0.0003	LEXUS	ES 300h	GTYX10036041
11	0.0004	BMW	328d xDrive Sports Wagon	GBMX91002835
12	0.0004	BMW	X3 xDrive 28d	FBMX10029777
13	0.0004	Lincoln	MKZ (HEV)	HFMX10040046
14	0.0005	BMW	430i xDrive Convertible	HBMX10042636
15	0.0005	TOYOTA	PRIUS	GTYX10038747
16	0.0007	Lincoln	Continental	HFMX10040229
17	0.0007	Lincoln	Continental	HFMX10040229
18	0.0007	Volvo	XC60 T6 FWD	FVVX91002096
19	0.0008	Lincoln	Continental	HFMX10040936
20	0.0008	Lincoln	Continental	HFMX10040936
21	0.0008	CHEVROLET	IMPALA	GGMX10035417
22	0.0008	Jaguar	XF AWD	FJLX10031525
23	0.0008	Jaguar	XF AWD	FJLX10031525
24	0.0009	HONDA	ACCORD HYBRID	HHNX10040660
25	0.0010	CHEVROLET	IMPALA	GGMX10035067
26	0.0010	CHEVROLET	VOLT	GGMX10036202
27	0.0011	Land Rover	Range Rover Evoque Cabriolet	HJLX10041369
28	0.0011	LEXUS	GS 200t F SPORT	GTYX91002766
29	0.0013	HONDA	ACCORD HYBRID	HHNX10040134
30	0.0013	Volkswagen	Eos	AVWX10004529
31	0.0013	Volkswagen	Eos	AVWX10004529
32	0.0013	Volkswagen	Eos	AVWX10004529
33	0.0014	BUICK	ENVISION AWD	GGMX91002683
34	0.0014	CHEVROLET	IMPALA	GGMX10035415
35	0.0015	Ford	MKZ	HFMX10040576
36	0.0015	CHEVROLET	CRUZE	DGMX91001335
37	0.0015	TOYOTA	TACOMA 4WD D-CAB V6 MT OFF-ROAD	GTYX10037434
38	0.0016	BMW	M4 GTS	GBMX10039343
39	0.0016	Ford	Fusion FWD	HFMX10040099
40	0.0016	Ford	MKZ	HFMX10040091
41	0.0016	Jaguar	XF AWD	FJLX91002440
42	0.0016	Jaguar	XF AWD	FJLX91002440
43	0.0018	Ford	Explorer AWD	GFMX10035158
44	0.0018	Ford	Explorer AWD	GFMX10035158
45	0.0018	Jaguar	XF AWD	FJLX10031523
46	0.0018	Jaguar	XF AWD	FJLX10031523
47	0.0018	Porsche	Boxster	HPRX10041242
48	0.0018	TOYOTA	TACOMA 4WD	GTYX10037173
49	0.0019	BUICK	REGAL AWD	EGMX10024287
50	0.0020	Ford	Mustang	FFMX91002327
51	0.0020	Ford	Transit Connect FWD	HFMX10040692
52	0.0020	CHEVROLET	K15 SILVERADO 4WD	HGMX10041924
53	0.0020	CHEVROLET	K15 SILVERADO 4WD	HGMX10041924
54	0.0020	HONDA	ACCORD L4	GHNX10036974
55	0.0020	Kia	Forte	HKMX10041689
56	0.0020	MASERATI	QUATTROPORTE GTS	HMAX10040324
57	0.0021	BMW	I8	EBMX91002202
58	0.0021	CHEVROLET	CRUZE	EGMX10024031
59	0.0021	Kia	Sportage	HKMX10038278
60	0.0021	MITSUBISHI	MIRAGE G4	HMTX10038807
61	0.0021	TOYOTA	TACOMA 4WD	GTYX10037100
62	0.0021	Volvo	XC90 T8 AWD	GVVX10037775
63	0.0022	HYUNDAI	SONATA HYBRID	GHYX10034755
64	0.0022	MAZDA	MAZDA6	HTKX91003172
65	0.0022	TOYOTA	PRIUS v	GTYX10036136
66	0.0022	TOYOTA	SIENNA AWD	HTYX10042003
67	0.0022	HYUNDAI	SONATA HYBRID	GHYX10033917
68	0.0023	Jaguar	XJ Supercharged	EJLX10024305
69	0.0024	HONDA	ACCORD	GHNX10037916
70	0.0024	HONDA	ACCORD L4	GHNX10036966
71	0.0025	BMW	I3 REX	HBMX10041978
72	0.0025	Ford	Escape FWD FFV	HFMX10039827
73	0.0025	HONDA	ACCORD L4	GHNX10037011
74	0.0025	KIA	K900	GKMX10035021
75	0.0025	Mercedes-Benz	GLA 45 AMG 4MATIC	FMBX10032582
76	0.0026	HONDA	ACCORD L4	GHNX10038093
77	0.0026	BUICK	CASCADA	GGMX10039349
78	0.0026	HYUNDAI	Sonata	GHYX10035944
79	0.0027	Ford	Escape FWD FFV	HFMX10039829
80	0.0027	Ford	Escape FWD FFV	HFMX10039829
81	0.0027	CHEVROLET	CRUZE	DGMX10020213
82	0.0027	HONDA	ACCORD L4	GHNX10036979
83	0.0027	Kia	Sportage	HKMX10038275
84	0.0027	Mercedes-Benz	AMG SLC 43	HMBX10043539
85	0.0027	LEXUS	GS F	GTYX10037135
86	0.0028	BMW	X6 xDrive 35i	GBMX91002854
87	0.0028	Ford	FUSION FWD	HFMX10040556
88	0.0028	Ford	FUSION FWD	HFMX10040556
89	0.0028	Ford	Mustang	FFMX10030991
90	0.0028	HONDA	ACCORD	GHNX91002760
91	0.0028	Mercedes-Benz	AMG SLC 43	HMBX10042050
92	0.0029	FORD	Explorer	GFMX10037126
93	0.0029	FORD	Explorer	GFMX10037126
94	0.0029	BUICK	LACROSSE AWD	GGMX10034689
95	0.0029	Kia	Sorento	GKMX91002414
96	0.0029	VOLKSWAGEN	Jetta	HVGA10043724
97	. . .	. . .	. . .	. . .
98	0.3106	RAM	3500 Cab Chassis 4X4	HCRX10042175
99	0.3665	RAM	3500 Cab Chassis 4X4	HCRX10042173
100	0.3665	RAM	3500 Cab Chassis 4X4	HCRX10042173
101	0.4342	CHEVROLET	G3500 EXPRESS 2WD CUTAWAY CH	GGMX10036377
102	0.4342	CHEVROLET	G3500 EXPRESS 2WD CUTAWAY CH	GGMX10036377
103	0.4342	CHEVROLET	G3500 EXPRESS 2WD CUTAWAY CH	GGMX10036377
104	0.6778	CHEVROLET	G3500 EXPRESS 2WD CUTAWAY CH	GGMX10036664
105	0.6778	CHEVROLET	G3500 EXPRESS 2WD CUTAWAY CH	GGMX10036664
106	0.6778	CHEVROLET	G3500 EXPRESS 2WD CUTAWAY CH	GGMX10036664

To handle transcription, I had to use a formula to pull each data value into the appropriate column. I could have had an error or problem or there may be a latent defect in the spreadsheet. I checked the top entry, Austin Martin, but it looks like the problem is in the source data. Also, I'm not familiar with the Kia product. Regardless, I wanted to see how NMOG+NOX actually worked out.

As I pointed out before, I prefer to have NOx as a separate metric from NMOG or any other organic compounds. But given how a catalytic converter works by oscillating between lean and rich, it sort of makes sense as a converter efficiency metric.

Bob Wilson

 

Hi Bob,

It appears the EPA 17actrr.xls file contains NMOG+NOx results for individual test cycles, but not a category for "composite" that I can find. For example, the BMW I8 has 0.0000 g/mi in the "charge depleting UDDS" test cycle, but has non-zero values in the other two test cycles listed. Meanwhile, the CARB cert for the 2017 BMW I8 reports the "Composite NMOG+NOx" as 0.024 g/mi (https://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2017/bmw_pc_a0080426_1d5_u2_phev.pdf).

Am I looking at the same EPA file you're using?

 

We are looking at the same XML file although I have a local copy that I'm doing some research and analysis. For example I plotted the NMOG+NOX vs NOX and the distribution of points helped me understand that is a way to look at the rich-lean cycle of catalytic converters. It also applies to diesel SCR systems.

The difference between the PDF and the XML file is the XML has data from individual cars in specific tests. The CARB PDF appears to be some sort of fleet summary "NMOG AND FLEET AVERAGE INFORMATION." The PDF looks like a requirements and limits versus tested, vehicle performance.

The XML file has three entries for the BMW i8 reflecting separate tests. Use the PDF to see if the car passes the CARB standard. As I pointed out before, I'm more interested in the Federal limits and looked at them because they apply to Alabama . . . an anti-CARB state.

Bob Wilson

 

I personally find the CARB PDFs easier to use. They do have "NMOG AND FLEET AVERAGE INFORMATION", but the following pages have the actual certification data (page 3 (of 4) for the BMW 328d, for example). The CARB PDFs also have evaporative emissions data on the same page. VOC emissions are as significant as NMOG emissions from an environmental/air quality perspective, and should be incorporated into the overall emission profile in my opinion.

On the other hand, the PDFs have emissions data on only one vehicle or vehicle family, thus you have to look at hundreds of different PDFs to see emission profiles of all vehicles (see Subject Top Page: Passenger Car, Light Duty Truck, and Medium Duty Vehicle Executive Orders - 2017 for example). EPA's files are easier to use in that case. I also wish CARB would be more consistent in post-decimal significant figures. They usually go out three or four places, but sometimes only two, which makes direct comparisons more difficult.

For me, the "composite" data are the most useful since they present a value that incorporates all test duty cycles..

Your summary table is useful nevertheless, and validates my original assertion that diesels can be essentially as clean as the cleanest gasoline vehicles, since two of the top ten vehicles in your table are diesels (328d xDrive and X3 28d).

 

At one time, I used CARB data to compare and contrast Jetta TDI with earlier generation Prius. Now I prefer the EPA data files, CSV and XLS, because it means I can see across the industry.

Indeed, BMW knows how to do it.

BTW, here is a quick snippet of the BMW i8 data:

	MODEL_YEAR	2017	2017	2017
1	MFR_SHORT_NM	BMW	BMW	BMW
2	ENGINE_FAMILY_NM	HBMXV01.5I8P	HBMXV01.5I8P	HBMXV01.5I8P
3	EVAP_FAMILY_NM	HBMXR0090I8P	HBMXR0090I8P	HBMXR0090I8P
4	Represented Test Veh Make	BMW	BMW	BMW
5	Represented Test Veh Model	I8	I8	I8
6	VEHICLE_ID	VX64010	VX64010	VX64010
7	VEH_CONFIG_NUM	0	0	0
8	Displacement (L)	1.5	1.5	1.5
9	Curb Weight (lbs.)	3455	3455	3455
10	GVWR (lbs.)	4090	4090	4090
11	ETW (lbs.)	3750	3750	3750
12	TEST_DRIVE	4	4	4
13	TEST_DRIVE_DESC	4-Wheel Drive	4-Wheel Drive	4-Wheel Drive
14	TRANS_TYPE	A	A	A
15	TRANS_TYPE_DESC	Automatic	Automatic	Automatic
16	TRANS_TYPE_OTHER_DESC
17	NUM_TRANS_ON_GEAR	6	6	6
18	TRANS_LOCKUP_YN	Y	Y	Y
19	CREEPER_GEAR_YN	N	N	N
20	VEH_FUEL_CAT
21	VEH_FUEL_CAT_DESC
22	HYBRID_YN	Y	Y	Y
23	Set Coef A (lbf)	-16	-16	-16
24	Set Coef B (lbf/mph)	0.084	0.084	0.084
25	Set Coef C (lbf/mph**2)	0.01395	0.01395	0.01395
26	Target Coef A (lbf)	35.4	35.4	35.4
27	Target Coef B (lbf/mph)	0.165	0.165	0.165
28	Target Coef C (lbf/mph**2)	0.01527	0.01527	0.01527
29	TEST_NUMBER	EBMX10032484	EBMX91002202	EBMX91002201
30	TEST_PROC	81	3	21
31	TEST_PROC_DESC	Charge Depleting UDDS	HWFE	Federal fuel 2-day exhaust (w/can load)
32	TEST_FUEL	62	61	61
33	TEST_FUEL_DESC	Electricity	Tier 2 Cert Gasoline	Tier 2 Cert Gasoline
34	CERT_INUSE_CD	C	C	C
35	VEH_CLASS	LDV	LDV	LDV
36	VEH_CLASS_DESC	LDV/Passenger Car	LDV/Passenger Car	LDV/Passenger Car
37	CERT_REGION	FA	FA	FA
38	CERT_REGION_DESC	Federal	Federal	Federal
39	STANDARD_LVL	T3B125	T3B125	T3B125
40	STANDARD_LVL_DESC	Federal Tier 3 Bin 125	Federal Tier 3 Bin 125	Federal Tier 3 Bin 125
41	Useful Life Miles (k)	120	120	120
42	EMISSION_NAME	NOX	NOX	NOX
43	Rnd Emission Result (g/mi)	0.0005	0.001	0.0067
44	Cert Level (g/mi)	0.001	0.001	0.007
45	Emission Standard (g/mi)	99.999	99.999	99.999
46	ADDITIVE_DF
47	MULTIPLE_CAT_DF	1.114	1.114	1.114
48	USE_NMOG_NMHC_RATIO
49	RATIO_OF_NMOG_NMHC
50	DIESEL_ADJ_FAC_VALUE
51	DOWN_DIESEL_ADJ_FAC_VALUE
52	REACT_FACTOR
53	CO	0.7		0.8
54	CO2
55	CREE	0	192	232
56	ETHANOL
57	H3C2HO
58	HCHO
59	HC-NM
60	HC-NM+NOX
61	HC-NM+NOX-COMP
62	HC-TOTAL
63	METHANE	0		0.0019
64	METHANOL
65	N2O
66	NMOG	0.01	0.0011	0.0067
67	NMOG+NOX	0	0.0021	0.0134
68	NOX	0.0005	0.001	0.0067
69	OPT-CREE
70	PM

Bob Wilson

 

I drive semi and that's a good point on starting and stopping the engine. the other problem is def and scr system on semi trucks break youll be dealing with the problem until you sell the truck.