Second Lap: A Single Nissan LEAF Goes Head-to-Head for Range and Economy

By RecargoJames · July 19, 2012

To simulate our "commute to work," we drove from Venice, Calif. to the California Science Center, just south of downtown Los Angeles.

For our first range-vs-economy comparison, we ran two Nissan LEAFs up and down a mountain to see how they'd compare. One car was driven in the "D/Normal" mode, while the other was run in the "Eco" mode. Unfortunately we had a couple variables which may have skewed the results: the cars had different firmware versions, and both cars were driven by different people.

To correct the inequity, we decided to run just one LEAF, with one driver, over the same route twice—a round-trip distance of 27.4 miles, just short of the national commute-to-work average.

According to the Federal Highway Administration's (FHWA) 2009 National Household Travel Survey (NHTS), the average number of vehicle miles traveled per day was 28.97. To simulate our "commute to work," we drove from Venice, Calif. to the California Science Center, south of downtown Los Angeles.

Unlike the trip to Mt. Wilson with steep grades, this trip would be relatively flat, with a starting elevation near sea level, and ending up at 185' elevation. Instead of freeways and two-lane highways, the second test was performed on stop-and-go city streets.

The car's tire pressure was checked prior to the tests. During both "commutes to work," the climate control was set to 72 degrees/Auto, the windows were rolled up, and the headlights were turned off. The only difference between the two trips were "Eco" mode and "D/Normal" mode.

Second Test Results

	Eco Mode	D/Normal
Starting Range	111	115
Range remaining at CSC	85	85
Miles/kWh Used at CSC	4.1	4.1
Ending Range	64	65
Miles/kWh Used at End	4.5	4.2

This time, the playing field was leveled by driving the same car twice (no conflicting firmware issues), and with the same driver. We discovered a slight improvement in economy when the LEAF was driven in the "Eco" mode. The faux-commute was fairly short in distance, but if the numbers were run for an entire year, the economy savings could really add up.

As one PluginCars community member states: "... all Eco does is encourage you to drive more like a hyper-miler than a jack rabbit. That is where the mileage gain comes from ... not anything magically different."

Comments

· VoltSkeptic (not verified) · 47 weeks ago

Definitely a better test than the original, but one should use the fuel burned, not some computers (gu)estimate of how much farther you can drive. So State of Charge (SoC) should be used instead of the 'Miles left' estimate. Unfortunately the LEAF does not have such a gauge on the dash, however the miles/kW does use the fuel consumption in its calculation so it is a good indicator.

Eco does two things: (1) shifts the acceleration sensitivity and (2) allows more regeneration off the accelerator. Effectively #1 enables #2. When the car is moving there is more regen when one is not touching the accelerator (like B in the Prius), depressing the pedal lightly will enable coasting, and a little heavier engages forward propulsion. D does regen too, just less and it takes a lighter press to engage coasting & forward propulsion. From a standstill the first half of the pedal range has in lighter acceleration, on the second half (towards the floor) things catch up to D mode. Flooring the pedal has the same effect in D or Eco.

So the improved economy on the downhill trip from CSC makes complete sense, it is a nearly 8% miles/kW improvement (4.5 vs 4.2) if the gauge was reset at CSC. If not, the difference in economy is larger: to get up to 4.5 if 50% was at 4.1, you need to do 4.9 for the 2nd half which is almost 17% improvement on the downhill (which isn't minor).

· Iletric (not verified) · 47 weeks ago

So, technically speaking, if it was done in Kansas (i.e. flat, no hills terrain) it would be equal for both trips. The only difference is due to more regen in Eco mode. I wish they drove at least 50 miles to see more pronounced difference, if applicable (particularly on flat terrain).

· NeilBlanchard · 47 weeks ago

I would posit that what makes Eco mode better is *not* because it has more regenerative braking on the accelerator pedal. Free-wheel coasting is far more efficient since you are accelerating the car less and then you directly use the kinetic energy to continue moving the car forward.

Case in point: Wayne Gerdes (who coined the phrase "hypermiling") drove a Mitsubishi i MiEV 124 miles on a single charge -- and he used coasting in neutral a lot, and only used regen in D, Eco, and Brake when he needed to slow down. He managed to virtually *double* the EPA range, and free-wheel coasting makes this possible. Fine tuning the position of the accelerator pedal is not good enough to coast easily and consistently.

I've only driven a Leaf briefly, and only driven an i MiEV for a short time, as well. I am a practiced ecodriver, though and I am habitual about driving in the most efficient manner I can.

Neil

PluginCars

Nissan LEAF

Second Lap: A Single Nissan LEAF Goes Head-to-Head for Range and Economy

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