In Sea Change, Electric Cars Top Greenest Vehicle List

By · February 07, 2012

Mitsubishi i electric car

Mitsubishi i electric car

The American Council for an Energy-Efficient Economy today announced that the Mitsubishi i electric car was rated the greenest car in its 14th annual environmental rankings of cars and trucks. The small EV unseated the Honda Civic Natural Gas car, which held the top spot in ACEEE’s green car rankings for the past eight years—and represents a sea change in green car technology. In this year’s rankings, the all-electric Nissan LEAF came in second place. This year's impressive showing for electric cars likely establishes future dominance for EVs in green rankings from ACEEE and other organizations.

The CNG Civic tied with the LEAF for second place—but it’s important to understand that ACEEE researchers evaluated pollution from electric cars using an average of the nation’s electric grid mix, whereas in many parts of the country, cars that use electricity as fuel have a much smaller environmental profile. “It’s completely possible that electric cars would do much better in other parts of the country,” said ACEEE lead vehicle analyst Shruti Vaidyanathan, in an interview with

The Mitsubishi i and Nissan LEAF were the only two plug-in cars included in ACEEE’s evaluations this year. Vehicles have to sell in quantities above 1,000 units to be included—and cannot be offered as lease-only cars.

The Toyota Prius Plug-in Hybrid is not on the market yet, and was therefore not included this year. But ACEEE conducted an “initial study” of the Prius PHEV. “If included, the plug-in Prius would be in the top-third of list, beating the regular [no-plug] Prius, but just barely,” said Vaidyanathan.

The Chevy Volt plug-in hybrid was included this year, but did not make the Top 12 list—because, similar to electric grid mix, ACEEE used a national average of American’s driving patterns (rather than common scenarios in which Volt drivers almost always drive using electricity). Those average driving patterns—knows as “vehicle utility factors,” derived from data from the Society of Automotive Engineers—states that the Volt is within its all-electric range about 65 percent of the time. “It all depends on driving habits,” said Vaidyanathan. “If you take a lot of short trips and plug it in often, of course, it will be better.”

The Volt is also penalized for its relative heaviness. ACEEE uses vehicle weight as a proxy for pollution resulting from manufacturing. On the other hand, the Mitsubishi i scores well because of its low weight.

Beyond the top-scoring electric cars, and the Civic CNG, the list was dominated by gas-electric hybrids. Six hybrids were among ACEEE’s greenest—with three small lightweight gas-powered cars completing the Top 12.

As more electric cars emerge on the market—more than 10 will be introduced this year—pure EVs and plug-in hybrids could begin to rule the very top of the ACEEE green rankings. If evaluated based on cleaner electric grid mixes, where electric cars are most popular, electric cars could completely dominate the greenest list for years to come.


· smithjim1961 (not verified) · 6 years ago

A CNG vehicle should never have been named a top green car when methane leakage is considered. Methane is 21 more powerful as a greenhouse gas than CO2. The precise amount of methane leakage is not known but estimates say several billion tons of methane leak to the atmosphere each year. When methane leakage is taken into account natural gas is more polluting than coal.

· Anonymous (not verified) · 6 years ago

Methane is unstable in our atmosphere and is oxidized quickly (max 4 years ) . It is otherwise an inert gas and does not damage the ozone layer . CO2 pollution is among the least dangerous considering the other forms , such as heavy metals , SOx , NOx , aromatic compounds ( dioxins , benzene etc ) . If one does not use natural gas then the other mainstream option is to use oil , so please be rational in your comments . There is almost no human activity that does not damage the environment .Thank you .

· Michael Chiacos (not verified) · 6 years ago

I just commented to ACEEE to incorporate some additional data on EVs, which will really enable us to make better comparisons on the green score of EVs versus hybrids and gasoline cars. I think you will all be interested in my suggestions or may even contact ACEEE as well to do with a similar request!


Thanks for your work with your greener cars list. I work on policy and advocacy around sustainable transportation and always make sure to spend some time with your report each year. I also manage Plug in Santa Barbara, working on EV issues on the Central Coast of California.

I was surprised to see that the two electric cars profiles were not rated much higher than a Prius and that the Mitsubishi i barely beat the natural gas Civic, while the Leaf tied it. This was surprising to me as both the Leaf and i achieve around 100 mpg equivalent, and fuel consumption is a big proxy for environmental impact as for traditional cars only 10-15% of impact is due to manufacturing, with the lions share due to use (obviously this changes a bit for hybrids and electrics).

I spent some time with your methodology, and suggest two updates to your report, or for incorporation into your next report.

• Share fuel consumption in mpge for EVs, like the EPA and Fuel do. Most consumers have no idea what the Leaf getting 3.1 miles/kWh means, but they do understand when the EPA rates it at 99 mpg equivalent. You state the Natural Gas Civic in gasoline equivalent, why not for EVs?

• I understand your EVs get treated as though they fueled up on a national grid, whereas most of the EVs have been sold in areas that have much cleaner grids (CA, OR, WA, etc.) It would be useful to rank the cars based on national grid, but also calculate the score for the cleanest grid states and the dirtiest states. Here in California, EVs reduce GHGs by 75% compared to gas cars due to our clean grid (and getting cleaner), whereas West Virginia might be a place where a hybrid would do much better than an EV. Thus you could give a “range” of scores for EVs, depending on their state grid averages. I think this would be quite easy to do and would help sort out people’s questions around EVs and environmental benefits greatly. Also, here in my part of California we are seeing about 50% of EV drivers are adding 2 kW of solar, which is enough to power their EV about 12,000 miles/year. It would be interesting to see the score of an EV powered exclusively by solar. Maybe an EV driving on sunshine might make it into the 80s or 90s!

I’d appreciate hearing your thoughts on my comments and if you can calculate these things in a follow up addendum or in next year’s report.


Michael Chiacos
Energy Program Transportation Specialist
Community Environmental Council
Santa Barbara, CA

· · 6 years ago

Does anyone have a video review, or any review of the US version of the MiEV yet? I've read it's bigger than the version overseas. Just curious how that will affect handling what not. The price is certainly appealing. I'm hoping that it will do well in the government crash tests.

· Kei Jidosha (not verified) · 6 years ago

Well deserved first place for the Mitsubishi i.

tterbo - lots of reviews;

US version is wider, longer and heavier to pass NHTSA crash, rollover, and "American tastes" compliance. Battery and motor are the same with lower gearing to handle the weight. Unfortunately range suffers compared to euro and home market design. More is not always better.

· · 6 years ago

That's unfortunate that the iMiev came out so high. While I like the car, it's short range, I fear, will mean that it won't be able to reduce very many ICE miles and will likely do additional harm by scaring people away from EVs.
The fact that the Volt can easily replace an ICE for so many people, should mean it should get a very high rating.
ie 65% ICE use on a Volt that can replace 90% of the ICE vehicles is better than 100% EV in an "i" that can only replace 10% of ICE vehicles and only those that don't account for very many miles.

· · 6 years ago

Keep in mind, folks: ACEEE is not thinking about market factors, such as cost, value to customer, and how many might get sold or put on the road. ACEEE is only pushing the car (with its stats) through an algorithm--so a light car like the Mitsu i can win, even if it's relatively unappealing and doesn't sell very well.

· · 6 years ago

I hope that the Mitsubishi does sell well. I hear a lot of Volt drivers are reporting extremely low gasoline usage then what can the Mitsubishi i accomplish with its much greater all electric range? OK, so the i has a lower range than the Leaf and maybe the Focus as well but what does it really matter? If the prospective buyer does her/his homework they will be buying a vehicle with enough range to do what they need it to do. It's all a matter of degree. Why knock the i or the Leaf or any other all electric for "low" range when most people's usage fits within those vehicle's ranges perfectly? The i is also within financial reach of a lot more people than the Volt, too.

I think that some of the best ICE miles to reduce are those who have very short commutes since warm up emissions are so horrible.

· · 6 years ago

As the price of both gas and electricity goes up (both likely), the vehicle that can deliver the best efficiency will become more desirable. And, if there are lower fixed costs (purchase price + insurance) then it makes a car like the i even more attractive. 60 miles is a lot more than either my wife or I drive regularly in a day. For more unusual days the opportunity to charge can be used. For really long trips we can rent a gas car or take public transportation. Too many people want to own a tool (like a long range ICE) that is used only a few times a year when if they looked at the financials and convenience more closely, they'd realize that renting is a much more intelligent way to go.

· · 6 years ago

With its French twins, the Mitsubishi i was the best selling EV in Europe last year. I didn't like it at first sight, a car so tall and narrow, but it drives much better than it looks.

· · 6 years ago

@Dan · "As the price of both gas and electricity goes up (both likely), the vehicle that can deliver the best efficiency will become more desirable."

I think most EVs will only differ by 10% of so in terms of efficiency (in the next few years). I think that is unlikely to sway anyone - price, size & features are likely to be more important.

I spent some $30 last month on electricity. Unlikely I'll give up Leaf for a Mitsu i - to make that $30 go to $27.

· · 6 years ago

@EVNow - If you could figure out a cost per mile considering ALL factors, initial price, insurance, and costs per mile, the i would be 0.33/mile and the Leaf at 0.42/mile (the main difference being $8k more and a slightly higher insurance).

But, you're definitely right that the running costs are not very different: even at $.50/kwh (a rate I hope never to see), the difference is only $100/year more for the Leaf. But, it's still more efficient and there are people who strive for efficiency who would prefer this over having another seat in the back that would rarely get used (I know, I'm a minority in this country that thinks this way). Or to put it another way, if you could buy a LEAF that got 99 MPGe and the exact car iLEAF that cost the same and had the same features and but also got 112 MPGe - wouldn't you choose the more efficient one?

I personally don't view the i as a "sacrifice" - that is some kind of small car discrimination ...

· · 6 years ago

@Dan, A 60 mile range may work for you but for me it is a non-starter. My LEAF easily handles my 66 mile grocery shopping trips even in winter, when the range is reduced by cold. The "i"? Not likely.

Efficiency isn't everything, the tool still has to function adequately. For dense urban environments the "i" might be a good choice. For those of us who live with western sprawl? Not so much.

· · 6 years ago

@dgpcolorado, a 66 mile grocery trip? Wow. I realize that to replicate a lifestyle as it currently exists for a lot of people, even a 100 mile range may be too little (I work with a guy who lives about 50 miles from work, so he couldn't get a Leaf - a Volt would do, but both are too expensive for him).

Yes we're talking about plug-ins, but I sometimes feel we (myself included) are blind to how much we spend to remain in an inefficient situation (living far from work or shopping) instead of trying to remedy that situation. I personally can't imagine spending an hour in a car a couple (?) times a week just for grocery shopping. I don't think sitting in any car (I did drive a Leaf and it was a very pleasant drive) is improving my quality of life. Perhaps many people living in ex-urbs now with hundreds of thousands of dollars invested in a home (without good prospects to sell) MUST continue those commutes. However, I wonder if sometimes (even in my own case, where I'm a little farther [can't bicycle easily], holding on to such a situation might be investing good money after bad. Why not relocate to be closer to what you need to do? You'll save money and have more time for the things you really like to do in life. But, that's just my perspective.

I do like the Leaf and drool over the Model S ... but initial costs, which will be difficult even with the i, are too difficult to justify.

· · 6 years ago

@Dan, I retired here to the mountains after living in cities or suburbia my whole life. I dislike travel and chose to live in the area I would travel to, instead. Yes, it isn't an efficient way to live, especially compared to living in a rabbit-warren urban environment with public transportation available. I rationalized my new rural living by figuring I was "cashing in my chips" after bicycle commuting my whole career. Now, the advent of EVs (plus my solar panels) make even my remote rural living less fossil-fuel dependent than before. I also bicycle commute down to town, a very rugged ride, at least 50 times a year. And since I don't go jetting all over the world and have an efficient house, my carbon footprint is vastly lower than the average American. Even way out here in the boondocks.

As for the grocery shopping trips, I make them every ten to twelve days when I run out of perishables, so the time involved is trivial and the drive is highly scenic and pleasant. I can't imagine shopping twice or more a week and didn't even when I lived in the city.

Being able to live in the mountains with deer, chipmunks, and mountain lions as my neighbors, is far more pleasant than my former life in surburbia. It is nice to be able to see the Milky Way from inside my house when I turn out the lights and to be able to make day trips to such spectacular places as Arches, Canyonlands, and Black Canyon National Parks. And now, thanks to my LEAF, I last bought gas on December 19th and my ICE car is still almost half full, so my driving is mostly electric.

But I'm glad most people prefer living crowded together in cities or this lovely place wouldn't be so peaceful and quiet.

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