New Study: Just How Much Can Range Vary in an Electric Car?

Technical Input By

Written by Liz Najman
Researcher
June 23, 2023

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An Example: Range Varies from Car to Car

The data below is all shown in units of vehicle efficiency, which is mi/kWh. Why does efficiency matter? It is the most accurate way to estimate a car’s range! Efficiency numbers are translated into range numbers by multiplying the efficiency by battery size.

Say you own a Chevrolet Bolt that either came with a 66 kWh pack or was upgraded under the recall. The official EPA efficiency rating is 3.57 miles per kWh, which translates to a range of 259 miles (= 3.57 mi/kWh * 66 kWh). However, when you’re actually driving your Bolt, the efficiency, and thus the range, may fall anywhere on this plot on any given day. The plot below shows the frequency with which our Bolt population hits different efficiencies.

• The average, observed Bolt efficiency value is 4.36 miles per kWh. For the 66 kWh pack, this means a 287.76 mile range – around 19 miles more than the EPA predicts. However, some cars fall on the less efficient side of the spectrum and may only see as few as 149 miles of range, while more efficient Bolts may be lucky enough to enjoy a range of up to 426 miles. How can you plan a trip if you don’t know where your Bolt falls?

Range Varies From Day to Day

The chart below compares efficiencies for two different Chevrolet Bolts – the most and the least efficient models in our testing sample.

• The most efficient Bolt in the group averages 5.2 mi/kWh efficiency, which translates to a range of around 343 miles if it drives under the same conditions for the full, 66 kWh battery. On a good efficiency day, that car can get a range of 508 miles – which is more than some full-sized gas cars can go on a full tank. But, on a bad day, it may only see a maximum range of 178 miles.

• What separates the good days from the bad days? It comes down to weather, driving conditions, and how you’re driving. On a 72 degree day, cruising along residential roads to run errands, you’re much more likely to see a high range than driving through the mountains in 20 degree weather with a snowboard mounted on your roof rack.

Compare those numbers to the least efficient Bolt that we track. This car has an average efficiency of 3.5 mi/kWh and a maximum projected range of 231 miles, driving under consistent conditions. Its minimum range is 95 miles, and its best-case maximum range is 367 miles.

(values in miles)

Why the difference between Chevy Bolt cars?

1. First, there is some natural variation between the cars and their batteries. This is true for any manufactured item, and there is a whole branch of statistics that try to understand this variability.
2. Second, the least efficient car is in a region that gets much lower temperatures than the most efficient car. While the most efficient car was observed in temperatures that ranged between 57℉ and 86℉, the least efficient car saw temperature as low as 7℉.
3. Finally, drive style and terrain make a difference. This is exactly the same as in a gas car. Aggressive driving, fast acceleration and uphill direction all use more energy. The only difference with an ICE car is that with an EV, highway driving uses more energy and reduces range, while city driving is more efficient.

Here is what happened in other vehicles in the study.

Ford F-150 Lightning Efficiency

When you look at the Ford F-150 Lightning efficiency stats, the first thing you notice is that they are relatively inefficient compared to other popular EVs. This is because they are heavy vehicles with relatively poor aerodynamics.

• Using the average efficiency value of 2.65 miles per kWh, the standard range battery pack would get an average range of 253 miles while the extended range would get 350 miles.
• Using the lower-end efficiency value you get a projected range of 93 miles for the smaller battery pack and 124.5 miles for the larger.
• Finally, using the higher-end efficiency value, you can see ranges as high as 427 for the standard range and 571 for the extended range.

Note that in this high efficiency case, the F-150 Lightning is almost certainly not pulling anything, would be on a flat surface or decline, and is in very mild weather.

Volkswagen ID.4 Efficiency

It just so happens that all of the ID.4s in the cohort have the larger, 82 kWh battery packs, which makes it easy to compare them. Below is the most and least efficient ID.4.

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• The least efficient VIN in the test group had an average efficiency of 3.45 mi/kWh, which translates to a range of 283 miles. This is nearly 82 miles less than the range calculated for the most efficient ID.4 – 365 miles.
• The spectrum of likely range predictions for the least efficient ID.4 is 138 - 427 miles, while the most efficient ID.4 is likely to see a range between 201 - 529 miles.

Ford Mustang Mach-E Efficiency

• The average, observed Mach-E efficiency value is 3.53 miles per kWh, which means a 232.98 mile range for the 66 kWh pack and 303.6 miles for the 86 kWh pack.
• On the less efficient range of the spectrum, a Mach-E may only see 108 miles of range (140 miles for the 86 kWh trim).
• More efficient Mach-Es may be lucky enough to enjoy a range of 358 miles (467 miles for the larger battery).

.avif)

Nissan LEAF Efficiency

For the Nissan LEAF, using a 40 kWh battery, the EPA range estimate is 151 miles. This is fairly close to the range for the average condition, average efficiency LEAF, although in great conditions, almost any LEAF can exceed that.

Tesla Model 3 Efficiency

For the Model 3, we ran the numbers using the Long Range trim with a 75 kWh battery. This configuration has an EPA range of 358 miles, which is not achieved by cars under the average conditions. The most variation is under “great” conditions: ideal temperature, dry and flat roads, and stop-and-go traffic.

How was this data collected?

Recurrent has been using on-board diagnostic devices in real cars around the U.S. for over a year to help understand, and share, real-world data about EV performance and range. We look at cars in temperatures as low as -13 degrees Fahrenheit and as high as 113 degrees. All cars go about their regular daily lives, including road trips, commutes, traffic, and errands so we can see how real-world conditions affect range.