When it comes to electric vehicles, range is one of the most important numbers. However, how accurate are EPA estimated ranges?

Edmunds has been keeping tabs by testing an assortment of electric vehicles, and the results are pretty surprising as many easily exceed their EPA estimates. In particular, the Porsche Taycan 4S traveled 323 miles (520 km) which is 120 miles (193 km) more than its EPA rating.

It’s far from alone as the Audi E-Tron Sportback, Chevrolet Bolt, Kia Niro EV, Hyundai Kona Electric, Ford Mustang Mach-E and Volkswagen ID.4 all traveled farther than their estimates. However, there was something curious about Tesla – all of their vehicles fell short of EPA estimates.

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Tesla wasn’t pleased with the results, so they reached out and blamed the company for stopping their tests when a range of zero miles was indicated. Tesla argued that the batteries still had juice and Edmunds was underestimating their actual range.

Given that, Edmunds ran the test again using a Model 3 Standard Range Plus, a Model 3 Long Range and a Model Y Performance. They also brought along a Ford Mustang Mach-E and Volkswagen ID.4 for comparison.

The vehicles were driven around a 7.5 mile (12.1 km) long course at 65 mph (105 km) until the batteries died. The Mach-E traveled 7.3 miles (11.7 km) past zero, while the Model Y Performance made it 12.6 miles (20.3 km). The ID.4 went 12.9 miles (20.8 km) while the Model 3 Standard Range Plus and Model 3 Long Range traveled 17.6 miles (28.3 km) and 25.9 miles (41.7 km), respectively.

The results mean some Teslas would be capable of meeting their EPA estimates, but only if they were driven past zero indicated miles remaining. However, as Edmunds noted, there is “no indication” of how much farther you can go and “for all we knew, the cars could stop at any moment.”

The publication also stated “the majority of Teslas we’ve tested so far — four of the six — do not meet their EPA estimates even allowing for a safety buffer. Furthermore, almost every other EV Edmunds has tested met or exceeded EPA estimates without the need to include their safety buffers.” As a result, you might want to take Tesla ranges with a grain of salt.