ACEEE Green Car Ratings: No Respect for Weighty Tesla

By · January 27, 2014

Smart ED Cabrio

The Smart Electric Drive Cabrio rocked the "Greenest Car" rankings from ACEEE. (Jim Motavalli photo)

Say hello to the "Greenest" car on the U.S. market, the Smart Fortwo Electric Drive. It got a score of 59 in the annual ratings, released today, from the American Council for an Energy-Efficient Economy (ACEEE), but that doesn’t mean that every electric car won the group’s respect. In fact, some were outright dissed.

ACEEE uses a complex set of variables to determine its green scores, and weight and manufacturing emissions matter a lot. Shruti Vaidyanathan, ACEEE’s lead vehicle analyst, told me that building a car can produce 20 percent of its lifetime emissions, which is higher than I’ve heard from the group in the past. A 37 for the zero-emission Tesla Model S with 85-kilowatt-hour battery pack? The same score as the Toyota Tacoma pick-up? Why?

“We rated the Tesla this year, and it’s a heavy vehicle with a heavy battery,” Vaidyanathan said. Weight is one of the biggest determinants.” The lighter 60-kWh Model S was rated 38. Besides the Smart, the electric car that did especially well, at number 3 on the list, is the Nissan LEAF. “That’s a very light electric car,” Vaidyanathan said, “around 3,500 pounds.”

There are both “Greenest” and “Greener Choices” lists, with the latter showcasing cleaner cars within categories, including SUVs and trucks. Thus the Ram 1500 HFE and Nissan Rogue are on the “Greener Choices” list, but the Chevy Volt is not, nor are any cars with plugs. The Chevy Volt didn’t place, even though it scored a decent 50. Three versions of the Prius trumped on the “Greener” list with best compact (Prius C), midsize (Prius) and midsized wagon (Prius V). All scored (barely) higher than the Volt.

Averaging the Grid

Obviously, electric cars are generally greener in states with cleaner grid electricity. EV scores do reflect the grid, but not locally—the national grid is averaged for ACEEE’s evaluation purposes.

Plug-in fans will probably rankle to see cars like the conventional Mitsubishi Mirage, with a score of 54, on the “Greenest” list but the Honda Fit EV (56) and RAV4 EV (43) nowhere to be seen.

Other EV rankings include the Chevy Spark (58), Fiat 500e (57), Honda Accord Plug-In Hybrid (52), Ford Focus Electric/C-MAX and Fusion Energi (all 51), and Porsche Panamera S E-Hybrid (37). That last one's gotta hurt.

My first impression of this year’s ACEEE list is that the ratings put a little too much weight on weight, and the scoring methodology doesn't fully consider the benefits of electric drive efficiency. Maybe ACEEE, in the spirit of promoting vehicle efficiency, should lighten up a bit on the weight penalty, at least until EVs roll out in greater numbers in 50 states.

The "Meanest"

Incidentally, there’s also a “Meanest” list, and the Ram 2500 (Class 2B) truck and Bugatti Veyron are close competitors there. The Ram gets an 18, and the Bugatti a 19. It’s hardly a surprise to see two Rolls-Royces there, the Phantom Drophead Coupe (23) and the Phantom EWB (also 23).

Here's the full "Greenest" list:

The

The "Greenest" cars on the market.

Comments

· · 42 weeks ago

I think they lose my acceptance of ther evaluation method when EVs are not all at the top. I own a toyota C and think it's a great car but the Leaf has actually got to be a greener car.

· · 42 weeks ago

Weight is important, but it comes after drivetrain efficiency and aerodynamic drag. Here is the results from the X-Prize Knockout Round that show this:

The measured MPGe of the teams in this round -- remember this is the Combined number from the City, Urban, and Highway tests:

American HyPower 54.5 Hybrid
Spira 84.8 ICE (E10)
FVT eVaro 152.5 Hybrid (serial)
Zap 111.0 EV
Tata 134.3 EV
Electric Raceabout 128.1 EV
AMP'd Sky 86.7 EV
West Philly (MS) 63.5 Hybrid
West Philly (Alt) 53.7 Hybrid
Global-E 50.4 Hybrid
Li-ion 182.3 EV
Aptera 140.1 EV
TW4XP 107.0 EV
WWU 92.5 Hybrid
Tango 86.8 EV
BITW 51.1 ICE (diesel)
X-Tracer (#72) 180.0 EV
X-Tracer (#79) 188.8 EV
Illuminati 119.8 EV
Enginer 53.0 Hybrid (electric/ICE w/ steam heat recovery)
Edison2 (#95 Alt) 97.0 ICE (E85)
Edison2 (#97 MS) 101.4 ICE (E85)
Edison2 (#98 MS) 80.3 ICE (E85)

I think these results speak for themselves! The electric cars are in general, giving much better efficiency, and several of those (the X-Tracer, FVT, Tata, and the Aptera) also have excellent acceleration. The Li-ion, Illuminati, TW4XP, and Edison2 (among others) were not as quick -- the Li-ion and Edison2 cars are through to the finals, though. I am sad that neither the FVT eVaro nor the Illuminati Seven made it through, due to (relatively) minor technical reasons. They failed at the moment (which is how racing/competitions work, to be sure), but I think their problems are solvable, and the strong merits of their vehicles are obvious.

The Aptera is through, but still a bit disappointing -- it's aero is equal or better to anybody (save the X-Tracer), but their efficiency seems to have suffered. It barely betters the Tata, which is "just" a well executed EV conversion of a decent but ordinary hatchback. The Global-E had an ignition mapping error that made their number lower.

So the lowest MPGe of an electric drive; the AMP'd Sky was 86.7MPGe (Tango was 86.8), while the best of a car with an internal combustion is the Edison2 #97 at 101.4. (Actually, the FVT has a ICE powered generator onboard, but did not need it *at all* in the X-Prize. It would be great to see how the eVaro does for MPGe in charging mode!) The hybrids all were all below the 67MPGe -- except the WWU at 92.5 (and the FVT).

The average of the 12 vehicles using electric drive MPGe (I'm including the FVT in this) was 134.7MPGe

The average of the 6 hybrids (not including the FVT) was 61.26MPGe (Please note, these are all parallel hybrids?)

The average of the 5 internal combustion drive cars was 82.92MPGe

The X-Prize results table does not include weights, but I daresay that the average weight of the internal combustion cars was lowest (the Edison2 and Spira are all much lighter!).

The best aero drag is on the X-Tracer, followed by a very close group including the Aptera, Edison2, Li-ion.

As many have said, the X-Prize is setting a very high standard (which is both good and bad). They are essentially looking for the complete package, and virtually no glitches. Even the well financed/professional teams had several glitches. I would have set up the X-Prize a bit differently; to measure (and therefore emphasize and encourage) the four main things that need to be improved to get the maximum efficiency.

Those four critical things are; from most important to least important (as I am interpreting the Knockout results):

* Drivetrain Efficiency
* Aerodynamic Drag
* Weight
* Rolling Efficiency

· · 42 weeks ago

@Neil,

I'm pretty sure you're missing the point of counting weight. They are claiming that the weight affects the impact of the manufacturing of the car, not its fuel efficiency.

Blindly taking weight (or in other cases I've seen purchase price) as an indication of the environmental impact of manufacturing the car is deeply flawed, especially when comparing cars that are as apples-to-oranges as EVs to ICEVs.

· · 42 weeks ago

Several things I think are dumb about this. First, saying "building a car can produce 20 percent of its lifetime emissions" is dumb, because not all cars have the same after-manufacturing emissions. So whose emissions are we talking about? If fueled by clean energy, an EV will have 100 percent of it's lifetime emissions from building the car. Second, when it comes to the car, emissions from manufacturing is an ancillary issue that is neither constant, nor should it really be looked at with much significance. To do so is short sighted, as if nothing else in this world will ever change.

If you have clean mining, clean plant power, and clean everything when building a car, emissions from building it can be zero. If it's an EV and powered by clean energy, its emissions from use can be zero. The car could weight a billion pounds and it would still be green. The only problem comes from sharing of resources. If humanity is successful in raising the entire world from poverty and into energy rich abundant lives, will their be issues with not enough raw materials to go around? Maybe, but that's a sharing issue. Not a green issue.

· · 42 weeks ago

+10, Skotty, on all counts.

Also consider that the Smart, which earned the highest rating, has the lowest utility. Two passengers, almost no cargo space. Great for a single commuter, but not very useful for a typical family.

Following ACEEE's scorecard to its logical conclusion, the greenest vehicle would be an electric unicycle.
(Which will be on the market soon)

· · 42 weeks ago

--"A 37 for the zero-emission Tesla Model S with 85-kilowatt-hour battery pack? The same score as the Toyota Tacoma pick-up? Why?
“We rated the Tesla this year, and it’s a heavy vehicle with a heavy battery,” Vaidyanathan said. Weight is one of the biggest determinants.” The lighter 60-kWh Model S was rated 38."

So... apparently ACEEES doesn't use actual EPA MPGe.... but rather makes it's own distinctions based on factors such as weight. Do they even factor in regen braking (which makes the weight of an EV MUCH less of a factor)??

Tesla Model S - 89 MPGe, 4647 lbs
Smart Fortwo EV - 107 MPGe, 2150 lbs

So despite more than DOUBLE the weight... regen braking does make the weight factor MUCH less of a determinant.

· · 42 weeks ago

Brian... I get your point about weight being a factor in the energy costs of vehicle manufacturing.

But ACEEES does NOT take into account the recycleability of the components that are the main cause of the weight. The battery pack is a huge portion of the weight... but that pack will not be thrown away and crushed at the end of life... as was probably assumed.
This is yet another assumption that is fine for gasoline cars, that is NOT fine for EVs.

· · 42 weeks ago

Brian... I get your point about weight being a factor in the energy costs of vehicle manufacturing.

But ACEEES does NOT take into account the recycleability of the components that are the main cause of the weight. The battery pack is a huge portion of the weight... but that pack will not be thrown away and crushed at the end of life... as was probably assumed.
This is yet another assumption that is fine for gasoline cars, that is NOT fine for EVs.

· · 42 weeks ago

@Joeviocoe,

To be clear, I completely disagree with the way they are counting weight, I was just responding to Neil's post about weight's effect on driving efficiency. My point is that if you compare two gasoline cars, most of the components will be about the same - more weight just means more / beefier ones. But with an EV, the components are completely different, so the equation will be different.

Recycling is another excellent point. Then there is reuse - many EV batteries will likely find a second life as a stationary power source. If these batteries then enable the grid to be cleaner by stabilizing intermittent renewables, shouldn't that count as negative emissions?

· · 42 weeks ago

Yes Brian... kinda what I meant about recycling Tesla batteries (reuse is the correct term I should have used).

Tesla is likely to reuse old batteries for use at their Superchargers (to buffer the grid, and/or solar power)

· · 42 weeks ago

I agree with the criticism of the methodology behind these ratings. You should take weight into account but you need to filter the weight with category metrics relating to embodied energy. An example is Aluminum alloys, which if derived from it's original ore is one of the most energy intensive materials. But if the Aluminum is recycled it uses only 5% of the original energy when converting bauxite ore to refined Aluminum. Also according to Aloca 90% of the Aluminum used in the automotive sector is recycled, and 75% of all the aluminum produced since 1888 is still in use because of recycling. The current recycled content level of Aluminum in the Building Products segment is 85%. Any attempt to rank vehicles by their embodied energy or carbon footprint that does not allow for these important distinctions is as useless as it is lazy. Having the Tacoma pickup and the Tesla rated the same is duplicitous and misleading, the future energy saving from the collection and recycling of the aluminum and the redistribution of the battery packs into grid applications will have continuing benefits. With prudent and wise additions to the grid the Tesla will become greener and greener, the Toyota not so much.

I understand that you might not be able to characterize every parts unique carbon footprint, but you could certainly take the gross weight by material category included savings from recycled content and then come up with a reasonable relative ranking.

· · 42 weeks ago

I agree with the criticism of the methodology behind these ratings. You should take weight into account but you need to filter the weight with category metrics relating to embodied energy. An example is Aluminum alloys, which if derived from it's original ore is one of the most energy intensive materials. But if the Aluminum is recycled it uses only 5% of the original energy when converting bauxite ore to refined Aluminum. Also according to Aloca 90% of the Aluminum used in the automotive sector is recycled, and 75% of all the aluminum produced since 1888 is still in use because of recycling. The current recycled content level of Aluminum in the Building Products segment is 85%. Any attempt to rank vehicles by their embodied energy or carbon footprint that does not allow for these important distinctions is as useless as it is lazy. Having the Tacoma pickup and the Tesla rated the same is duplicitous and misleading, the future energy saving from the collection and recycling of the aluminum and the redistribution of the battery packs into grid applications will have continuing benefits. With prudent and wise additions to the grid the Tesla will become greener and greener, the Toyota not so much.

I understand that you might not be able to characterize every parts unique carbon footprint, but you could certainly take the gross weight by material category included savings from recycled content and then come up with a reasonable relative ranking.

· · 42 weeks ago

The Tesla Model S is almost 2X as efficient as a Prius, and about 4X better than a Tacoma. It takes at least 7.5kWh of electricity to produce a gallon of gasoline, so the energy to drive an ICE is huge.

This 'study' is ridiculous, and biased.

· · 41 weeks ago

I owned two Smart for two's, then two Nissan Leaf's and now own two Tesla's. My Smarts we're not battery but that doesn't matter since my comment has to do with the functionality of each vehicle.

When I operated Smarts and Leafs I had to keep a larger ICE car to handle all the situations for which the limitation of the local only errand runner cars were not capable. When I upgraded to Tesla's I was able to give up the ICE car and meet 100% of my transportation needs with solar generated electric power only.

The ACEEE rating system is completely useless since it does not factor in the vehicles ability to actually perform the functions needed by the vehicle users. Based on this rating system a Hot Wheels kids toy battery car would get top honors.

With the vehicles given top ratings by ACEEE in almost every case a typical family would still need a larger ICE car to meet their daily needs. The rating is seriously flawed by not taking into account the cars ability to meet users needs. After trying Smart Cars and Nissan Leaf's in my quest for a 100% solar electric solution I finally found the Tesla model S and now no longer need to also own and maintain an ICE car to meet all my transportation needs. I operate my 100 % electric house, charge two Tesla's and still sell surplus solar back to the utility. With the Leaf the range was so limiting I had to augment it with a Gasoline powered car. With the Tesla I can operate 100% on solar generated electric.

The ACEEE rating methodology is severely flawed by not taking into account the actual ability of the vehicle to perform all the functions the user needs. The ONLY car currently on the market that can completely replace an ICE vehicle is a Tesla Model S. All the rest are extremely limited, local errand runners. I loved my Leafs for short local driving but found they were completely useless for more than 15 one way miles of freeway speed travel.

Assigning high ratings to limited range, slow charging, limited utility cars actually sets adoption of more efficient electric vehicles by the general public back. What I learned driving Nissan Leaf's was that I really needed a Tesla. The Leaf's required constant range management and planning, charged very slow and lost battery capacity quickly. With the Tesla I never think about range, charge quickly and have experienced no capacity loss in my batteries. I fully expect the Tesla to last four or five times longer than the Leaf and provide many many times more travel miles.

Bottom line is I personally find the ratings to be completely worthless in the real world of automotive use.

· · 38 weeks ago

Smart ED is one of the best EV's available.

6200 miles. No problems. Flawless. Incredible little car. Very quick, smokes many cars. Has style.

I get 80 miles per charge. love this car so much and i have the only matte grey smart electric with led daytime running lights in my town. Very unique. And very cheap, $139 a month. Mini electric Mercedes.

Many Tesla owners have given my cars props and like it.

Highly recommended 2nd or 3rd Car/EV.

· · 38 weeks ago

Who would have thought the "greenest car" would be so much fun and so cool?!

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