How Far Is Enough?

By Bill Moore

Posted: 02 Feb 2012

ANSWER: 437 kilometers or if you wish, 271 miles.

That’s the average driving distance most respondents to the Accenture consumer survey believe is required of a fully charged electric car before it needs recharging. So, reports a recently published study out of Columbia University’s Earth and Environmental Engineering Department. Consumers expect this because this is what they have become accustomed to. Most petroleum-fueled ICE-age vehicles typically have driving ranges of from 234 miles (Dodge Ram 1500 pickup) to 383 miles (Toyota Camry and Honda Accord). The Chevrolet Silverado 4WD claims an incredible 491 miles (that must be one whopping fuel tank).

So, it’s little wonder the average consumer expects an electric vehicle to be capable of similar range performance. They’ve built their lives around that expectation.

Or have they?

Not according to the Columbia study, which analyzed 2009 population data from the National Household Travel Survey of some 150,000+ American households. What they discovered is that while gasoline car drivers expect a vehicle to travel many hundreds of miles/kilometers before needing to refuel, in actual day-to-day practice, they drive only a fraction of that distance.

What the Columbia study discovered isn’t particularly new information. We’ve known for years that the average commute (see page 6) is typically between 30-40 miles, with the U.S. national average about 27 miles. Over half of those weekday trips into work are under 10 miles; with more than half of the total miles driven being 40 miles or less. So, while the average IC-engine vehicle can drive 300 or more miles, their owners typically only drive one-tenth of that distance on a daily basis.

Most drivers seem to have a good grasp of how far they usually drive on a daily basis; after all, they do five days a week. (When I used to commute, my drive was 12.5 miles one way. My wife’s daily drive is 5.5 miles one way.) What they don’t have a good grasp of is what the capabilities are of an electric car, which the authors define as both battery and electric hybrids or PHEVs. The Accenture study cited by Columbia notes that, on average, 30% of the respondents said they had ‘enough’ understanding of the technology to make an intelligent buying decision; and in a footnote, Accenture researchers commented that they felt even this group likely overstated what they claimed they knew. Chinese respondents had the highest score (44%), Japanese, the lowest (20%); U.S. came in at 36%.

The people who have the best grasp of the capabilities of EVs are those who actually drive them, and here the Columbia researchers turned to U.C. Davis’ study of BMW Mini-E lessees in California. While 60% of the 72 drivers interviewed ‘agreed very strongly’ that an EV was suitable for daily use, 81% answered ‘Yes’ when asked, “Are there any locations you would like to be able to access in your Mini E but can’t or prefer not to because of range issues?”

Another important issue the study addresses is range variability. While OEMs and EV advocates usually discuss the range of these vehicles, it’s usually only in the context of what they are capable of under ideal circumstances or based on EPA tests. In fact, real world experience can produce range distances that can vary widely with driver skills, weather conditions, state of battery charge, etc. The Columbia study uses the Nissan LEAF as an example. Under ideal driving conditions, it has a range of around 135 miles, with LEAF owners reporting up to 130 miles. Run through two different EPA drive cycles (SAE-J1634 & LA4) reduces this to 74 and 100 miles, respectively. Run through winter driving in urban stop-n-go, and this falls to just over 60 miles, less than half that under “ideal conditions.” That’s a driving range variability typically not seen in an ICE vehicle.

The authors observe that most American households have the luxury of having more than one vehicle from which to select for a particular trip: the national average is 1.9 vehicles per household. Significantly, 39% of those vehicles aren’t even driven on a daily basis.

What they also found was that 95% of all individual trips are below 30 miles and 99% below 70 miles. Also, it turns out that my old commute of 12.5 miles is the national average (12.6).

They conclude, “Assuming the electric car is charged overnight only, a Nissan LEAF with a 62-138 mile range would be able to satisfy 83-95% of all travel days, depending on driving conditions as described before. A 2011 Tesla Roadster would be able to satisfy > 98.5% of travel days, assuming a minimum range of 0.85 times the EPA-labeled range.”

Download the full study at: http://www.solarjourneyusa.com/HowFarWeDrive_v1.2.pdf

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