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Posted at 07:14 AM ET, 03/14/2012

The Nissan Leaf on 80 Miles a Day


(Cars.com)

To put Cars.com's 2011 Nissan Leaf through a series of long-distance, boundary-pushing trips, I commuted in it for a week, about 43 miles each way.

The Leaf charges fully during the day using a Level 2 public charging station. At home, I plug the Leaf into a regular household outlet, so as I soon as I get home, it gets plugged in and it doesn't get unplugged until I'm ready to leave the next morning.

As the only editor at Cars.com to experience true range anxiety as a result of the distance I have to travel, we thought this would be a great test of whether other commuters in my situation should consider buying the Leaf.

Here are the week's trips, one by one:

Day 1

Work (Chicago) to home (Aurora): It's been a while since I drove the Leaf, and I'm encouraged by the starting stats: fully charged (12 bars on the battery-charge indicator) and 110 miles of predicted range. However, it's freezing outside (and a slightly warmer 40 degrees in the parking garage).

The ride home starts out roughly. Interstate traffic is nearly at a standstill, and only 17 minutes into the trip, my predicted range has fallen to 67 miles. I've traveled only 3.5 miles, mind you, so in addition to moving at a mind-numbing pace, I'm watching my range fritter away like lottery winnings.

Eventually, I get off the freeway and take surface streets since they're moving faster. At the halfway-home point, I get back on the freeway when traffic picks up speed. At this point, I'm a little worried. I've got 20 miles to go and only about 32 miles of predicted range left. The temperature is down to about 30 degrees, and the freeway speeds seem to drop miles faster.

I arrive home after driving 45.3 miles (in two hours), with 13 miles of predicted range left and only two out of 12 bars showing. That's about as low as I've ever gotten it, and I was concerned I'd end up calling roadside assistance.

Predicted Range Accuracy: To get this percentage, we subtract the number of miles driven (45.3 miles) from the Leaf's initial predicted range (110 miles), and then we divide that number into the miles of predicted range remaining at the end of the trip (13 miles).

For this trip, the predicted range accuracy was 20%. We started at 110 miles PR, drove 45.3 miles and arrived with 13 miles PR remaining.

In a monthlong test we performed late in 2011, the Leaf averaged better than 80%, but that test included short and long trips. Here we're testing only long trips.

Range Anxiety Rating (0-10): 9

Discovery: After driving the Leaf on highways at low and high speeds and on surface streets, one trait jumps out. Frequent braking — with minimal effort that comes from slow-and-go freeway traffic — seems to make the range much better compared with driving on surface streets, where you come to a full stop for 30 to 40 seconds and then accelerate again. The greater initial burst of energy needed to get the Leaf to full speed on surface streets drains the battery faster than the modest increases in speed on the freeway.


(Cars.com)

Day 2

Home to Work: Because the Leaf had run so low the night before, it only had time to reach 86 miles of predicted range (11 of 12 bars), even after 13 hours of charging. So that worried me a little. On the plus side, it was warmer out, with temps at 40 degrees. When I hit the freeway and was able to run at full speed (65 to 70 mph), the range dropped like, well, leaves in the fall. But then something happened. I hit bumper-to-bumper traffic for a stretch and went eight miles stop-and-go, but the predicted range didn't drop a mile; then I stayed at 35 mph for nearly 12 minutes. In the end, I got to work (40.6 miles) in 73 minutes with juice to spare, with the battery at three bars and 21 miles of predicted range remaining.

Predicted Range accuracy: 46 %
(We started at 86 miles PR, drove 40.6 miles and arrived with 21 miles PR remaining.)

Range Anxiety Rating (0-10): 7

Work to Home: Despite a full charge, the predicted range was lower, at 98 miles, and this plays into what Cars.com Managing Editor David Thomas posits: The Leaf "learns" from the last trip based on trip length and driving style, and it adjusts its predictions accordingly. We'll see how that holds up for the whole week. I got home in 88 minutes with four bars and 29 miles of predicted range left. Temps were around 40 degrees the whole way.

Predicted Range accuracy: 53%
(We started at 98 miles PR, drove 43.7 miles and arrived with 29 miles PR remaining.) Distance variations from day to day reflect slight route deviations that were my attempts to evade heavy traffic.)

Range Anxiety Rating (0-10): 6

Day 3

Home to Work: Chicago's "winter" continues to astound, as it is 50 degrees outside when I unplug the Leaf at 8 a.m. (It would hit 60 when I arrive at work.) The predicted range has gone up again, to 105 miles. Traffic is uneventful, and after 44.8 miles and 81 minutes, I get to work. No anxiety even once on this trip, with speeds ranging from 70 mph to stop-and-go. I arrive at the parking garage with 48 miles of predicted range left.

Predicted Range accuracy: 80%
(We started at 105 miles PR, drove 44.8 miles and arrived with 48 miles PR remaining.)

Range Anxiety Rating (0-10): 0

Work to Home: So much for spring. Leaving the garage, I notice it's gotten downright bitter, and the winds have kicked up to an alarming 30 to 40 mph. And they're headwinds. Great. The outside temperature at start says 50 degrees. Starting range is predicted at 109 miles, but after driving two hours to get home (including a stop for dinner), the temperature is down to 33 degrees, and predicted range is down to a feeble two bars and 13 miles left. I'm not sensing much learning here; perhaps the Leaf was forced to unlearn what it had learned. The strong headwinds and falling temperatures likely made an impact on range accuracy.

Predicted Range accuracy: 19%
(We started at 109 miles PR, drove 42.0 miles and arrived with 13 miles PR remaining.)

Range Anxiety Rating (0-10): 9.
With those winds, I was truly worried that the turtle-mode warning would light up on the dash.


(Cars.com)

Day 4

Home to Work: The bad news: I got home so late last night that the car was charged for only 12 hours, and the Leaf shows only 75 miles of predicted range and 10 bars. This certainly adds to range anxiety. The good news: The wind has died off, and the temperature is 48 degrees, at least in my garage. It drops to 40 by the time I arrive. Traffic is relatively light on the way to work, and I experiment with a new technique: I accelerate a little more than I need to - leaving plenty of room in front of me, of course - and then coast, regenerating power. Theoretically, this is less efficient than accelerating gradually and avoiding braking as much as possible, but it seems to make the predicted-range display happy. I arrive with three bars and 20 miles of predicted range left.

Predicted Range accuracy: 66%
(We started at 75 miles PR, drove 44.8 miles and arrived with 20 miles PR remaining.)

Range Anxiety Rating (0-10): 5, and that tailed off pretty quickly.

Work to Home: This is a little of a mixed bag. It is 44 degrees outside, but there are no winds. The Leaf is fully charged, with 12 bars and 101 miles of predicted range. The ride home is great; it takes only 74 minutes, which is about the best I can do, especially when 10 of those minutes were spent getting out the parking garage into downtown traffic. I arrive with four bars and 32 miles of predicted range left.

Predicted Range accuracy: 53%
(We started at 101 miles PR, drove 40.4 miles and arrived with 32 miles PR remaining.)

Range Anxiety Rating (0-10): 2

Day 5

Home to Work: Another fast trip, this time into the city. Temps have remained pretty constant between yesterday and today. The new acceleration technique seems to conserve a little more juice, and my anxiety factor is nonexistent. I get to work in 74 minutes with three bars and 22 miles of predicted range left.

Predicted Range accuracy: 40%
(We started at 98 miles PR, drove 42.7 miles and arrived with 22 miles PR remaining.)

Range Anxiety Rating (0-10): 0
The five-day test has done little to assuage our distrust of the Leaf's ability to predict its range, a position based on a year's worth of data.

Compare the last two trips: Starting temperatures (both 44 degrees) and ending temperatures (38 and 39 degrees) are similar. The distances (40.4 and 42.7 miles) are close. Average speeds (32.8 mph and 33.1 mph) are close. So why the 23 percentage-point difference between the trips?


(Cars.com)

The Leaf clearly responds to temperature changes. The colder it is, the lower the accuracy of the predicted-range readout. You'd think the Leaf could account for this, as our Chevy Volt does pretty reliably.

The test illustrates that prospective buyers must be realistic about their needs. Theoretically, the Leaf's "up to 100 miles" of range should serve an 86-mile round-trip on a single charge. Without charging at both ends of our journey, we'd never make the car's EPA-estimated range of 73 miles. In colder weather, we wouldn't even come close.

By Cars.com  |  07:14 AM ET, 03/14/2012

 
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