There are three main testing cycles used around the world to calculate official range figures for electric vehicles, and a fourth obsolete one that still occasionally shows up. They produce varying results, but you can still get a sense of how they compare.
Let's begin by introducing them. The United States uses the EPA (Environmental Protection Agency) test and it produces figures closest to what is seen in real-world tests. The European Union and some other territories rely on WLTP (Worldwide Harmonised Light Vehicles Test Procedure), which replaced the wildly optimistic and now obsolete NEDC (New European Driving Cycle) in 2019. The CLTC (China Light Duty Vehicle Test Cycle) replaced the NEDC in China and is usually the most unrealistically optimistic of the three.
The range of any vehicle fluctuates somewhat, since it is affected by its speed, load, and weather conditions, so drivers generally won't achieve official range numbers unless they drive conservatively and keep speeds low.
To make things a little confusing, though, not every automaker applies the results from the tests equally. For instance, the Porsche Taycan Turbo S has an EPA rating of 201 miles, but it's an anomaly in that drivers should easily be able to attain closer to 300 miles per charge in typical driving in good weather.
To get a sense of how the ranges of cars correlate under the different testing regimes, we looked at a number of cars sold in all of the main territories — US, Europe, and China — and compared their EPA, WLTP, and CLTC ratings, as well as a couple only sold in Europe and China. Interestingly, one one vehicle is advertised on its website with discontinued NEDC rating: the Xpeng P7.
The results were pretty eye opening. The percentage of difference between official range figures varied widely by automaker, and sometimes also widely between models from the same automaker. The upshot is there's not really a reliable way to compare the test cycles with any precision.
As a rule of thumb, though, consider the EPA figure to be the most realistic with only a few percentage points difference from what one might see in real-world conditions. The WLTP figure to be about 22 percent higher than EPA, and the CLTC number about 35% higher than EPA. CLTC also appears to be a few percentage points higher than NEDC.
If all this is unhelpful and you just want a more real-world figure, InsideEVs regularly performs range tests of its own. Because range estimates are most important when travelling long distances we do drives at a constant 70 miles per hour, running the battery down from empty to full with a switch in direction at the halfway point to account for losses or gains from wind and elevation.