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.
