By Colin Bird on November 14, 2011
When we first got the Leaf last winter — one of the snowiest on record in Chicago — we discovered that the EV’s range was totally unpredictable. In February, in mostly below-freezing temperatures, the Leaf would show erratic range numbers. In one instance, the range was only 24% accurate from the beginning to the end of the trip. No distance, condition or driver correlated definitively with the range results, according to Cars.com Executive Editor Joe Wiesenfelder.
The variations all the editors experienced were anecdotal, so we decided to study the numbers more. How does the Leaf fare under warmer, more welcoming conditions? And, more importantly, how does it fare after installing the Vehicle Control Module update, which was supposed to help better predict range?
The results were surprising. After going through a month’s worth of driving data (29 trips, totaling more than 350 miles in Chicago’s balmy September) we found that the computer’s predicted range was about 86% accurate on average.
We use the stated range at the trip's start, on average a predicted range of 91.06 miles. Then we looked at the length of the trip. Our trips averaged 12.25 miles, and the average remainder was 68.65 miles. That means — somewhere, somehow — we’re losing about 10 miles of predicted range.
Of course, the farther away you live, the more anxiety the predictions can cause. On one of our most inaccurate trips in September, we started with a 105-mile range, drove an unusually long 47.7 miles and were left with a 28-mile predicted range. The computer’s predicted range was off by about 30 miles, giving it just below 49% accuracy. That long trip was driven mostly on the highway, and we know that highway speeds tend to diminish the Leaf’s predicted range rapidly.
Despite the inaccuracies, when push came to shove and we drove the Leaf until it completely died, we were able to get 72 miles out of the EV, which is only a mile less than the EPA’s 73-mile range estimate.
Our recommendation is to watch the battery level gauge (the bars on the far right in the middle photo) rather than the LED mileage readout. That gauge will tell you the actual state of battery charge, which you can use to adjust your driving accordingly to get where you need to go.