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UCS Releases Biennial Ranking of Greenest Automakers; Honda Edges Out Toyota to Keep Top Spot

Average global warming and smog scores of MY 2005 vehicles. Click to enlarge.

The Union of Concerned Scientists (UCS) has released its biennial ranking of the greenest automakers, based on the average emissions of global warming (grams CO2-equivalent per mile) and smog-forming (grams NOx and NMOG per mile) pollutants from vehicles actually sold. For the fourth time in a row, Honda topped the organization’s rankings as the country’s greenest automaker.

Using government data, report author Don MacKenzie analyzed the performance of 10 classes of vehicles produced by the eight automakers which together represent 96% of the US car and light truck market for model year 2005—the latest year for which final data are available.

Combined scores of the top six automakers since 1998. A higher score is worse. Click to enlarge.

Toyota lost by only a nose, surging to second place by making significant cuts in global warming pollution, while Honda’s score, in turn, worsened compared to its 2003 performance. Only GM and Toyota saw their results improve from MY 2003 to MY 2005; the other automakers all experienced a worsening of their environmental scores. (Chart at right.)

Hyundai-Kia, Nissan and Volkswagen were in the middle of the pack, coming in third, fourth and fifth, respectively. Ford and General Motors, meanwhile, were at the back, and DaimlerChrysler placed last, earning the Rusty Tailpipe Award for the dirtiest automaker.

There is a huge gap between the cleanest and dirtiest automakers. The winners are using clean technology across their entire fleets. The losers are installing it piecemeal, or not at all.

—Don MacKenzie, author of the report and a vehicles engineer with UCS

MacKenzie rated each automaker on how its vehicles compared to the industry average on global warming and smog-forming pollution. Cars and light trucks account for 25% of the nation’s global warming pollution and 20% of its smog-forming pollution.

Honda and Toyota had better-than-average global warming scores in every class in which they competed. Despite producing pickup trucks and large SUVs, Toyota’s use of emissions-cutting technology across its entire fleet helped it to pull up just behind Honda, which did not compete in these vehicle classes.

Toyota’s ranking shows that size is no excuse for a dirty fleet. All of the automakers have the technology today to make all of their vehicles, from two-seaters to four-by-fours, a lot cleaner. And given the Supreme Court ruling confirming carbon dioxide and other global warming emissions are pollutants, it’s likely that federal or state efforts will succeed in requiring automakers to put that technology to work.

—Don MacKenzie

Ford was the cleanest of the Detroit automakers, finishing sixth. But if Ford had made the same progress cutting global warming pollution in its US fleet as it has with its European fleet, it would have finished in fifth.

GM, which placed last in UCS’ 2003 model rankings, moved past DaimlerChrysler by reducing its fleet’s smog-forming emissions. But the country’s largest automaker failed to improve its global warming pollution score since the last UCS automaker rankings. In model year 2005, GM sold the most vehicles rated at 15 mpg or worse in city driving.

DaimlerChrysler came in dead last with the worst scores for both smog and global warming pollution. Its cars and trucks emit 70% more smog-forming pollutants and nearly 30% more global warming pollutants per mile than those made by Honda.

The UCS analysis showed hybrids helped improve environmental performance while diesels generally held automakers back. Volkswagen’s diesel engines, for example, slightly improved its global warming score, but significantly dragged down its smog score. Hybrids, meanwhile, helped Toyota cut its global warming pollution fleetwide because the company produced them in large numbers. Honda and Ford, which produced fewer hybrids, did not see the same improvement.

The report also evaluated the impact of flex-fuel vehicles by calculating global warming emission averages for various levels of E85 usage: 2% (somewhat higher than actual usage), 50% (the level assumed by the government in the assignment of CAFE credits), and 100% (the maximum possible). The report concluded that flexible-fuel vehicles (FFVs) are currently doing more harm that good, as the increase in global warming pollution due to the fuel economy loophole for FFVs more than outweighs the theoretical savings due to alternative fuel usage.

The E85 currently available provides only a 16 percent reduction in global warming emissions compared with the gasoline it replaces, but automakers receive a 65 percent bonus on the credited fuel economy of FFVs. As a result, even if FFVs used E85 100 percent of the time, this would still not compensate for the fuel economy loophole. Manufacturers would do much more to reduce global warming emissions if they satisfied fuel economy standards by selling more efficient vehicles, rather than exploiting the dual-fuel loophole. In fact, if Nissan had actually produced a fleet of vehicles as efficient as it was given credit for, its global warming score would have been good enough to put it ahead of Hyundai-Kia in combined scores, into third place overall.



Mark A

Whats significant here is that these scores are TWO YEARS OLD! What was the delay in getting this story out?

With that being said, it would be interesting to see how things are today. Toyota has since introduced their new full size truck, so they also now have vehicles near the 15mpg number mentioned in the article.

Whats also significant is that GM and Toyota were improving in 2005, while the others were getting worse. Would be interesting to see if that trend is continuing. I guess we have to wait for 2009 to get the answer to that.

Max Reid

Hybrids have set a record for Mar-2007.

Prius 19,156
Camry 5,144
Highlander 2,501

Rx400 1,471
Gs450 181

Toyota Total - 28,453

Accord 385
Civic 2813

Honda Total - 3,198

Total of 2 companies - 31,651

Still the sales of Ford and Nissan are to come.

Those who claimed that hybrid sales are falling will keep quiet now.



"Record U.S. sales of Toyota and Lexus
hybrids have now topped the half-million mark."


If there was a hybrid available for about $18k I would buy it. But they're all currently out of my price range.


Your scooter still beats them all Cervus. (What's a little rain eh?)



Rain? In San Diego? In Summer? Surely you jest. :)

I've considered trading my Reflex on a new Burgman 400. Fuel economy is about the same and it's safer on the freeway because I'd have more power when I need it. It's a harrowing experience trying to pass anything on the Reflex.

David Cabral

In Massachusetts, there are hybrids available for $16,000 to $18,000. You would have to buy used though (Prius and Honda Civic Hybrid, model years 2003 to 2005).



Used ones of that vintage here are selling for pretty close to a new one. I think I'll hold my horses and wait until the Gen3 Prius or the Volt arrives. Until then, I'll scooter along.


Does anyone know where to find reports on mine-to-junkyard life-cycle environmental performance for auto manufacturing? I keep hearing all sorts of rumors about how dirty the manufacturing is for hybrids (nickel smelting, etc.)

I think this is probably ICE manufacturer FUD, like the infamous and ridiculous CNW Market Research study from last year. But I'm wondering about documentation of how clean hybrids really are for their entire life cycle?

I'm working on a post about this for Black Sun Journal, and I'd like to put this canard to rest once and for all. But I'm having a hard time finding reliable research.


The RX400 and the GS450 are such "mild" hybrids, I would hardly
be extolling the merit of their sales figures. It would be
more advantagious to praise the sales of "moderate" hybrids as
they are the ones making the difference in MPG. If Honda made
as many inefficient real work truck models, with the power and preformance of toyota, I think it would be alot closer to a draw between the top two hybrid manufactures. After all Toyota is the leader when it comes to actually making a high MPG hybrid that doesn't share a vehicle platform with a non-hybrid model. The Prius outsells all other hybrids combined. When that changes, then I will give Honda the all the accolades it deserves. I will be waiting for Honda to make a useful work truck for the service
and construction tradesperson. All the other major vehicle makers have a contender in this market segment. The Honda Ridgeline is great for all other uses, but just isn't a work
truck, no matter how you slice it. Its more SUV than a Truck.
Leave it to a bunch of concerned, pocket protector laiden,statistic compiling,planet cooling,carbon footprinted,
scientists to hoodwink us into thinking Honda is better corporation buy a nose. I'll keep hugging my neighbors Toyota Prius untill Toyota makes a moderate 6 cyclinder biodiesel Li-ion PHEV Tundra that I can buy and run on switchgrass juice from my local Robeck's or Jamba Juice. I wont hold my breath however.

AutoXprixe - 100MPG challenge

What a shame that GM, Chrysler and Ford lag so badly in hybrid sales.

Well done, Toyota -- current undisputed king of hybrids

AutoXprize - 100MPG challenge

March US auto sales prove that fuel efficiency matters

BMW Group –1.4% at 28980 (3/06: 28,352)
Chrysler Group –8% at 206,435 (3/06: 216,412)
Ford Motor Co –12.24% at 264,975 (3/06: 291,146)
General Motors –7.7% at 349,867 (3/06: 365,375)
Honda America +7.3% at 143,392 (3/06: 128,806)
Nissan North America +3.9% at 111,119 (3/06: 103,095)
Toyota Motor Co. +7.7% at 242,675 (3/06: 217,286)
Volkswagen –19.3% at 17,355 (3/06: 20,730)

Don MacKenzie

Mark, we used sales, fuel economy, and emissions data from model year 2005, which is the latest year for which final data are available. For 2006, only preliminary estimates are available, and we want to base our analysis to be a reliable reflection of the fleets each manufacturer is actually selling.

BlackSun, you can check out these studies for full lifecycle analyses:
The Argonne paper in particular gets into criteria other than energy and global warming pollution, but I'm not sure if the full paper is available free for download anywhere.

And William, if you've got a problem with our results, you can kiss this nerd's pocket protector!


note how Toyota was the only one to go down from 1998 to 2005.

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