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. WLTP 277.1 miles of all-electric range. EPA 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.