We then round down the range to the nearest 10-mile increment. We've been generally surprised at just how linear the decline in the battery's charge is, and that there aren't big drop-offs along the way to zero. We compile those data points into two trend lines that we use to extrapolate the last few percent of battery that we didn't use. We record the entire run with a VBox LapTimer or Driftbox and also record the battery state of charge and the vehicle's predicted range every five miles.
CAN YOU TAKE ZMATRIX AND EV TEST TOGETHER FULL
We start with a full charge and run at a GPS-verified 75 mph for as long as possible, turning around at the halfway point to end back in our office parking lot. We run our range tests primarily on the highways surrounding our Ann Arbor, Michigan, office, and we typically run them during the middle of the day, or on nights or weekends, when the traffic is lightest.
CAN YOU TAKE ZMATRIX AND EV TEST TOGETHER DRIVERS
Also, the EPA test cycles run at considerably slower speeds than drivers typically experience on our interstates. That means EPA range figures don't necessarily provide an exact comparison between any two vehicles. But we wanted to come up with our own real-world range figure for two big reasons: first, there's some wiggle room in the EPA's rules, and automakers are allowed to use different methods to arrive at that range figure. Every vehicle has a range number displayed on its window sticker, which is arrived at according to the EPA's methodology. Range is the all-important number for buyers of EVs, far more important than the vehicles' efficiency figures (MPGe). Another juicing option we've used from time to time is to charge a vehicle fully at our office and then haul it out to the test track on a trailer. We typically plug the test vehicles in at the array of chargers at the test track and charge them fully, which leaves us about a mile to get to the straightaway. Because the maximum power output of a battery pack decreases as the state of charge dwindles, we always do our standing-start-acceleration runs first with the battery as close to 100 percent as possible. For our performance testing-acceleration, braking, skidpad, top speed-we do modify the order in which we run the tests for EVs. But that's not necessary with EVs, since a fully charged battery pack doesn't weigh any more. We always top off the gas tank before weighing a vehicle. And the fact that we weigh every car we test allows us to track precisely how much heavier EVs are than comparable gasoline-powered vehicles. Whether a car is powered solely by electrons or not doesn't affect many of our tests, which include things like stuffing carry-on-suitcase-size boxes into the back of cargo areas, measuring how much a vehicle's pillars block outward visibility, or seating height. But the relatively recent influx of electric vehicles has caused us to alter our usual testing regimen in a few ways, and we've also added a couple of EV-specific tests for range and charging. It allows us to move from statements like "this car feels quicker to 60 mph" to definitive conclusions about speed, cornering grip, interior noise, cargo volume, and a host of other important vehicle attributes. This foundation of objective data combined with our subjective observations brings serious depth to our reviews.
Testing is a core tenet at Car and Driver, something that's been infused into everything we do since 1956.
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