Recently, Consumer Reports published the results of a test comparing the typical range a consumer might get driving either of two electric cars: the 2016 Tesla Model S 75D and the 2017 Chevrolet Bolt. In our evaluation, the Model S went 235 miles, and Bolt went for 250 miles. In the weeks since, CR's test has been discussed on many blogs, and Tesla has challenged our results.

Even though the Bolt outperformed the Model S in this range test, the Model S retains its position as Consumer Reports' top-rated ultra-luxury sedan.

All of Consumer Reports' car testing is designed to help provide shoppers with information that reflects how they’re most likely to use their vehicle on a day-to-day basis. When we test the range of any electric vehicle, it’s no different. To that end, our goal is not to set range records; our aim is to let owners of EVs know, on an everyday usage basis, how far they can expect a fully charged EV to go. This helps avoid range anxiety, a fear that an EV will run out of juice before the trip is finished.

“CR designs testing methodologies to enable the evaluation of all comparable products in a fair and standardized way," says Liam McCormack, VP, Research, Testing and Insights, Consumer Reports. “We look at the criteria which in our judgment are most important to consumers to evaluate products in an independent and fair manner.”

There are several steps we take to ensure we’re getting comparable results between EVs:

  • First, we make sure the car is fully charged.
  • We check tire pressure when the tires are cold to ensure that they are all inflated to the manufacturer’s suggested settings.
  • To ensure repeatability, we turn off the heating and air conditioning system, because hard acceleration and running the HVAC system can cut the range significantly, as can driving in very cold temperatures.
  • We make sure the car is in its version of normal drive mode, not extended range mode, because our goal is not to see what’s the maximum range an EV can get when pushed to its limits, but rather to see the total number of miles a driver should expect under normal circumstances.
  • We put our EVs into their less-aggressive regenerative braking mode; regenerative brakes help EVs recapture some of the energy lost in braking. Many EVs have a mode with aggressive regenerative braking that’s meant to capture more of that energy, but it can be an intrusive experience, making the brakes seem grabby, especially for drivers who are new to EVs.
  • Our EV range test involves some mixed driving, but much of it is done by driving a constant 65 mph on highways. If drivers were to meander on rural roads at 45 mph, for example, they might get even more range.
  • We test cars when they have between 2,000 and 3,000 miles on them to assure similar levels of break-in. This is especially important as the rolling resistance for the tires can change as they wear.