What the Heck Does NEDC and WLTP w/ RDE Mean Compared to the EPA???

Discussion in 'In the News' started by xcel, Jan 2, 2020.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    [​IMG] [​IMG] What were you reading on New Years Day instead of this?

    Wayne Gerdes – CleanMPG – January 2, 2020

    2020 Toyota Prius

    The standard bearer when it comes to automotive efficiency discussion.​

    With a number of new BEVs coming out of Europe providing a given WLTP efficiency rating – WLTP vs NEDC was required from Jan 2019 forward, that sounds like a good thing, right? More realistic and accurate is always better... Except when they are homologized to the U.S.' EPA, they get creamed and trying to get our head around this is daunting.

    Namely, if the Worldwide harmonized Light vehicles Test Procedures (WLTP) was supposed to provide a more realistic driving cycle and displayed efficiency result for A to B new car comparisons, why does it fall so short of real world efficiency and emissions?



    A Real Driving Emissions (RDE) test measures NOx, HCs, CO, and CO2 emitted while a given test vehicle is driven on the road with gas an onboard analyzer attached to the vehicles tailpipe while it travels local highways and suburban roadways. It does create a real-world emissions profile although the results are not in any way incorporated into the WLTP for efficiency ratings.

    Let us begin with the older New European Driving Cycle (NEDC) that was last revised in 1992. We all know it was a joke for efficiency results as did most Europeans. I will not bother bringing up Japans JC08 which was the equivalent of world record type driving results... On the NEDC, OEMs could make up the dyno drag coefficients and simulated Road LOADs, eliminate higher level trims, and the cycle never modeled a typical driving cycle "RESULT" in any number of ways.

    To comapre to the EPA test cycle(s), the Beating the EPA - The Why’s and How to Hypermile write-up includes all the test cycles that are currently used to produce your Vehicle Monroney Fuel Economy results today.

    The WLTP was introduced in an attempt to correct the NEDCs shortfalls and model more real-world results.

    There are actually 3 test cycles that can be used.
    • Class 1 – Low power vehicles with Power/weight < or = 22 (Mainly Indian vehicles)
    • Class 2 – Intermediate power vehicles with Power/weight between 22 and 34 (Smaller, low power vehicles from Europe, Asia, and India)
    • Class 3 – High-power vehicles with Power/weight > 34 (Most vehicles including most U.S. offerings)
    Within the WLTP test, the average speed has increased from 21.1 mph to 28.9 mph and top speeds have increased from 74.6 mph to 81.6 mph vs the NEDC. Time and distance on the dyno have increased from 20 to 30-minutes and 6.8 miles to 14.4 miles respectively.

    In addition, the WLTP enforces higher average and maximum power, quicker accelerations and decelerations, includes both hot and cold engine starts, and shorter idle periods.

    Dyno Measurements are also now taken at 73 degrees F (and CO2 values corrected to 57 degrees F) vs 68 to 86 degrees F.

    All well and good. Now let us consider 2 case study’s on modern models we are all used to seeing.

    4th gen 2016 – 2020 Toyota Prius

    EPA, the 2020 Prius L (formally Eco trim) and LE – Ltd are rated as follows:

    L: 58/53/56 mpgUS city/highway/combined
    LE – Ltd.: 54/50/52 mpgUS city/highway/combined

    The LE with its 15” wheels actually supply very similar efficiency as the L whereas the XLE and Limited take a hit for the 17” alloys.

    NEDC, the same Prius trims albeit pre-2019 since that was the switchover to WLTP occurred were rated as follows:

    L: 81/76/78 mpgUS Urban (city)/Extra Urban (Highway)/Combined
    LE – Ltd.: 71/71/71

    WLTP, the same 2020 Prius trims as follows:

    L: 76/69/73 mpgUS Urban (city)/Extra Urban (Highway)/Combined
    LE – Ltd.: 67/62/64

    Moving to the All-electric universe, consider the all-new 2019 Audi e-tron SUV.

    2019 Audi e-tron

    The first of many future BEVs from the Brand of Four Rings.​


    277.1 miles of all-electric range.


    204-miles of all-electric range.

    Need I say more?

    Tens of millions of Euro’s were spent to change the efficiency status to new driving cycle tests and the results were…. Underwhelming at best. All it takes is a 30 percent negative adjustment and they could call it good. It is if the European Union wants to talk about low emissions but are afraid of the hard facts so they softball them. :(
    BillLin likes this.
  2. Jay

    Jay Well-Known Member

    I don't trust any of the govt FE figures, especially the EPA. The EPA lets manufacturers supply their own FE numbers and the manufacturers don't even have to dyno their cars. They're allowed to "calculate" the results. The EPA charges a lot of money for their official stamp but they can't be bothered to actually test the cars. EPA only tests about 15% of the cars it "certifies"(!). Then there's the obvious political thumb on the scale when Hyundai/Kia calculate their numbers 1mpg off and get monkey hammered. Ford gets their calculation several mpg off and completely skate. In my experience, domestic manufacturers' cars struggle to meet their claimed EPA numbers while foreign manufacturers exceed their ratings by a wide margin.

    The market is wide open for private independent reviewers to test the fuel economy of the cars they review. There must be a thousand vbloggers that review new cars and none of them (to my knowledge) actually measures FE in any objective standardized way. Fail. The major auto mags refer to the EPA. Fail. Consumer Reports is the only major reviewer that actually tests the FE of the cars it reviews and they are finding wide discrepancies between their test results and the EPA ratings--just like the rest of us.
    xcel and BillLin like this.
  3. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Jay:

    I know of another...

    Saying that, the fines even for the domestics are to large to fake results anymore. All the large OEMs have multi-million dollar 5-test cycle cells and they are in continuous use not just completing the EPA 5-cycle on their own vehicles but any number of other test cycles including the WLTP and even on their competitors vehicles. I have seen it with my own eyes.

    I was quite disappointed in the fines Hyundai and BMW received over minor shortfalls vs Ford GM, and FCA with larger discrepancies but that is the way politics work in this country.

    All told, it is sad to see the WLTP so optimistic vs our own EPA which is actually pretty close to real world now with the 5-cycles and 18 to 20 percent negative offsets incorporated. Considering the non-Prime Prius, there are many drivers that can and do maintain > 65 mpg averages so the WLTP is not entirely F'ed up but they - we - are way off the front of the standard deviation curve for sure.

    Jay and BillLin like this.
  4. Trollbait

    Trollbait Well-Known Member

    The EPA might be testing less than 15% now, but that isn't the Agency's fault. They don't get to set their own budget. Want it changed, you got to convince the Congress critters.

    The German government let their domestics slide on diesel emissions. The treatment of Ford vs. Hyundai annoyed me too, but that's how politics appear to work everywhere.

    What is forgotten is that the government tests aren't about projecting what fuel economy to expect in the real world. They are intended for making a like comparison between different models possible for consumers. That actually isn't possible with Consumer Reports results as they test outside without controlling for variables. Wayne reports the weather for his steady speed results. The most I've seen from CR is a, "we don't test when it's wet out." Their test facility is in lower New England, so seasonal changes in weather and fuel formulations is going to have an impact in their results.

    Reporting fuel economy was an afterthought for the EPA test. Its purpose was for testing emissions. To better reflect what cars are actually emitting, the city and highway test cycles should be updated to better reflect how cars are actually driven now. That would also mean MPG results closer to what people would get on the street. That would be a big undertaking as how the new tests would impact current emission and CAFE regulations would need to be addressed, with likely requiring Congress to make changes to those.
    BillLin, xcel and Jay like this.
  5. SI_Prius

    SI_Prius Well-Known Member

    It's not all about the MPG, WLTP+RDE should get more real world CO, NOx, PM, HC emissions. Also note that cars released before september 2018 were not directly tested on WLTP, but were given a calculated value based on NEDC. And even after that date some exceptions apply, but it's is such a birocracy that I don't understand it.

    Here is a UK site that have the data, note that MPG is in UK gallons.
    In the CO2 section, there is a link to "available WLTP data" click on it for real WLTP data.
    The whole quote:
    # Note that prior to 6th April 2020, the first year car tax will be calculated on the CO2 results obtained under NEDC testing, or CO2 results from WLTP tests which are equivalent to what they would have been had the car been tested to NEDC standards. Follow this link to see the available WLTP data.

    For Prius I get from 94 (15" wheels) to 108 (AWD) g CO2/km. CO2 emissions directly translate to fuel consumption, as 1 liter of gas will emit 2.33 kg CO2. So under WLTP Prius consumes:
    - 4 l/100 km or 59 MPG (15" wheels)
    - 4.4l/100 km or 53 MPG (17" wheels)
    - 4.6 l/100 km or 51 MPG (17" wheels + AWD)

    Don't ask me why WLTP data is so secret, but apparently all cars in EU have still NEDC consumption data, even if WLTP tested they calculate what would the consumption be if it were tested under NEDC.

    Stupidity at it's max.
    BillLin, xcel and Trollbait like this.

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