Reviewing new cars in Europe, you start to notice how none of them ever seem to live up to their official Worldwide Harmonised Light Vehicles Test Procedure (WLTP) figures. If it’s an internal combustion vehicle, it can’t quite match the official efficiency numbers, while if it’s an electric vehicle, it always falls short of the advertised range, no matter how you drive.
The European Commission (EC) recently published data that reveals the fact that WLTP figures for gasoline or diesel cars is about 20%—it’s much worse for plug-in hybrids (PHEVs).
The EC mandated the installation of on-board fuel consumption monitoring devices (OBFCMs), and it became a legal requirement for passenger vehicles being sold in Europe starting in 2021. The new report is based on efficiency data it obtained from over 617,000 cars and nearly 7,000 vans, which found that gasoline models were on average 23.7% less efficient than their WLTP claim, while diesels did slightly better with an 18.1% gap.
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WLTP is better than NEDC but not as good as EPA
Even though the WLTP test cycle is an improvement on the NEDC that preceded it, there is still room to improve its accuracy for it to match the US EPA test cycle.
For PHEVs, the difference is 3.5 times greater. Most have an official estimate that they use under 2 l/100km (117 mpg), but the consumption monitor data found PHEVs on average used 4 l/100km (58.8 mpg) in real-world driving. This bigger gap was explained by the fact that PHEV owners don’t charge them as often as the WLTP guidelines expect, so they end up using a lot more fuel.
The EC says it expected this gap, and after reviewing dozens of cars in Europe over the last few years, a 20% discrepancy (more for gasoline and less for diesels) is what I’ve always observed. This is also obvious to most car owners, many of whom take to forums to discuss fuel economy to make sure their particular vehicle is working well and their results are consistent with what others are observing.
The WLTP test cycle was introduced in 2017 and was presented as an improvement upon the New European Driving Cycle, which had last been updated twenty years prior, in 1997. The new results published by the EC will probably bring along another similar transition to a new testing standard, like the one from 2017, and it could be implemented in 2026.
Since there will be an increasing number of vehicles on European roads whose efficiency and charging habits are being monitored, the EC will have even more data to piece together in the coming years, which will hopefully help it come up with an even better testing method to accurately represent efficiency and range.
The EPA test cycle used in the United States is considerably more accurate than WLTP, and it not only gives you a much better idea of a vehicle’s efficiency, but you can even hope to exceed the official figures in some vehicles; this is virtually impossible for WLTP figures, which are only achieved in strict laboratory conditions that can’t really be replicated in the real world.
The ultimate goal is to get people driving more efficient vehicles that produce less and less tailpipe emissions and eventually into fully electric cars. One of the report’s recommendations is to scrap current carbon dioxide (CO2) regulations, set targets for individual carmakers to meet CO2 targets for their entire range, and also have them sell a set minimum share of EVs.
This could not only have an impact on what powers cars sold in Europe in the next few years, but it may also force automakers to make smaller, lighter and more efficient cars; this could result in big SUVs being abandoned in favor of models that bring up the manufacturer's range-wide efficiency and emissions numbers.
