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Tested: Why Teslas Show Unrealistic Range Estimates Compared … – Car and Driver

In C/D testing, we found that Tesla’s range display indicator doesn’t adjust to account for driving conditions in the same way that other EVs’ distance-to-empty estimates do.
A recent

report from Reuters alleges that Tesla "rigged" the software in its cars to overestimate the estimated range remaining, leaving drivers disappointed when their vehicles couldn’t travel as far on a charge as advertised. A few California owners have now filed a proposed class-action lawsuit seeking unspecified damages.
In Car and Driver range testing, we found distinct differences in the way that Tesla EVs’ in-dash range displays operate compared with those from other automakers’ EV models. Put simply, Teslas don’t adjust the numbers on their range display to account for recent driving conditions in the same way that other EVs do.
We analyzed test results for several different models in our real-world 75-mph highway range test, in which we measure, every 5 miles, the indicated battery state of charge percentage remaining, the number of miles traveled, and the car’s estimated range remaining.

Because highway driving is less efficient than city driving, many EVs experience fluctuations in the car’s estimated range remaining, or distance to empty (DTE). The estimated range remaining often drops precipitously, and also inconsistently, as the car takes into account the higher speeds and lower efficiency of highway driving. That’s not the case with Tesla vehicles.

In a 2021 Tesla Model S Plaid, for instance, the car’s displayed range estimate falls at a remarkably consistent rate throughout the test. It starts off with an indicated 100 percent charge and an estimated range of 350 miles. For every 5 miles traveled, the predicted range drops by more than 5 miles at a time, but it does so at a rate consistent with a very simple formula: the battery’s state of charge multiplied by the EPA-estimated range of 348 miles. Throughout the test, the indicated range never deviates more than 2 miles in either direction from this calculation. We’ve noted a similarly linear pattern in our tests of other Tesla models including a Model 3 and a Model Y. However, with a destination entered, the predicted battery state-of-charge shown in the navigation system is more realistic, but it doesn’t affect the miles-to-empty readout.
Other electric vehicles show far more deviation in their DTE displays. In a 2023 Lucid Air Pure AWD, the display shows a 100 percent charge and an indicated range of 376 miles at the beginning of the test, against an EPA-rated range of 384 miles. The deviation between the indicated range and the expected EPA range fluctuates widely through the test, sometimes indicating a difference of just 1 mile below the expected EPA range but at another point growing to a difference of over 12 miles. This indicates that the car’s computer is adjusting the range estimate both upward and downward to account for differences in driving style, temperature, and other drive-cycle factors. Our test results for vehicles from other automakers including GM, Hyundai-Kia, and BMW show a similar pattern.
Of course, there are also inconsistencies in EPA range estimates to begin with, and there’s no perfect formula for estimating a vehicle’s range. (See our previous story on the secret adjustment factor that Tesla uses for more details on how the company gets such big range ratings to begin with.) But while Tesla isn’t the only automaker that is aggressive with EPA labeling, this difference in how its cars estimate the displayed range in the vehicle is at best optimistic and at worst misleading.
Despite being raised on a steady diet of base-model Hondas and Toyotas—or perhaps because of it—Joey Capparella nonetheless cultivated an obsession for the automotive industry throughout his childhood in Nashville, Tennessee. He found a way to write about cars for the school newspaper during his college years at Rice University, which eventually led him to move to Ann Arbor, Michigan, for his first professional auto-writing gig at Automobile Magazine. He has been part of the Car and Driver team since 2016 and now lives in New York City.  

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