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    frequently asked questions

    1. how do you rate the vehicles? (answer)

    2. i'm considering purchasing an online subscription. what exactly will i see once inside? (answer)

    3. has your book been reviewed? (answer)

    4. diesel-powered vehicles are highly efficient. why don't i see them in your "greenest vehicles" list? (answer)

    5. i can't find the vehicle i'm looking for on your website. do you have a rating for it? (answer)

    6. do you have green scores for used cars? (answer)

    7. how can i get a hard copy of the book? (answer)

    8. even though electric vehicles don't have tailpipe pollution, don't they still cause pollution from powerplants? (answer)

    9. speaking of evs, i don't see any this year. what happened to them and how do they score? (answer)

    10. are there any federal or state incentives available for purchasing a green vehicle? (answer)

    11. who is the american council for an energy-efficient economy? (answer)

    12. i have additional questions about green vehicles. where should i direct them? (answer)

    13. how can bookstores order aceee's green book®? (answer)


    how do you rate the vehicles?

    we analyze automakers' test results for fuel economy and emissions as reported to the u.s. environmental protection agency and the california air resources board, along with other specifications reported by automakers. we estimate pollution from vehicle manufacturing, from the production and distribution of fuel and from vehicle tailpipes. we count air pollution, such as fine particles, nitrogen oxides, hydrocarbons and other pollutants according to the health problems caused by each pollutant. we then factor in greenhouse gases (such as carbon dioxide) and combine the emissions estimates into a green score that runs on a scale from 0 to 100. the top vehicles this year score a 57, the average is 30 and the worst gas-guzzlers score around 14. further information can be found on the greenercars.com methodology page.

    a complete discussion of the ratings is given in our technical report, rating the environmental impacts of motor vehicles: aceee's green book® methodology, available from the aceee publications office.

    i'm considering purchasing an online subscription. what exactly will i see once inside?

    an online subscription will give you access to our database of every vehicle we have scored for the past seven years (model years 2000-2007; about 10,500 records in total). subscribers can search the interactive database (updated with new model releases throughout the year) and build custom lists for comparing vehicles. the "best of 2007" tables offer a sample view of the layout.

    has your book been reviewed?

    aceee's green book® has been widely praised as a valuable resource on vehicles and the environment. but don't take our word for it. see what others are saying.

    diesel-powered vehicles are highly efficient. why don't i see them in your "greenest vehicles" list?

    it is still an open question whether diesel engines can be made clean enough at a competitive price to extensively exploit their efficiency advantage in the u.s. market. most of the diesels on the market, such as volkswagen's jetta tdi (turbocharged direct-injection), score "inferior" in green book ratings even though they are more fuel-efficient than their gasoline counterparts. the jetta 1.9-liter tdi diesel automatic rates 35 mpg in the city and 42 mpg on the highway, for an overall average of 38 mpg. that's about 35 percent better than the 28 mpg average for the jetta with a 2.0-liter gasoline engine. but the diesel version is certified to a standard that allows it to emit, for every mile driven, more than eight times the amount of nitrogen oxide (nox) emitted by the gasoline-powered jetta, which now qualifies as a tier 2 bin 5 vehicle in the majority of the country.

    automakers are working to clean up the diesel vehicle. for example, ford is developing a version of the focus sedan that uses advanced control technologies targeted to meet california's ulev ii standards. it has equipped its laboratory test car with a special nox clean-up device in which a solution of urea in water is sprayed on the catalyst to selectively reduce nox from the exhaust stream. the vehicle also has a catalytic, soot-trapping filter to remove fine particles. widespread use of such systems is still some years away, particularly if a new chemical such as urea needs to be widely distributed along with ultra-clean diesel fuel. engineers at ford and other companies trying to slash diesel emissions are making up for lost time, since today's gasoline engines benefit from over three decades of experience with ever-tighter pollution standards.

    i can't find the vehicle i'm looking for on your website. do you have a rating for it?

    our free website includes the year's greenest and meanest vehicles, as well as the greenest vehicles in each size class, given in the best of 2007 tables. the full ratings for all vehicles are available through aceee's green book® online.

    do you have green scores for used cars?

    in addition to the model year 2007 listings, aceee's green book® online also contains ratings for all model year 2000 through 2006 vehicles. ratings for model year 1998 and 1999 vehicles are available in hard copy in the 1998 and 1999 editions of aceee's green book®, respectively. these can be purchased through the aceee publications office. ratings for older vehicles (model year 1997 and earlier) are not yet available.

    for earlier model years, fuel economy is an important determinant of greenness. so look for high-efficiency models on the federal fuel economy guide website.

    how can i get a hard copy of the book?

    aceee's green book® was produced in hard copy through model year 2003. they can be ordered from the aceee publications office.

    even though electric vehicles don't have tailpipe pollution, don't they still cause pollution from powerplants?

    yes, and we account for powerplant pollution in our ratings. we also account for the pollution caused by refining and delivering gasoline to the pumps for gasoline cars. electric vehicles score well even when powerplant pollution is taken into account because they are typically very efficient vehicles by design. more importantly, powerplant exhaust is not emitted "in your face" as street-level pollution that directly exposes many people, as it is for gasoline and diesel vehicles.

    speaking of evs, i don't see any this year. what happened to them, and how do they score?

    astutue subscribers of aceee's green book® online may notice that no electric vehicles have been analyzed for the past couple years. this is because we only include vehicles that are both readily accessible to the public and of which a non-trivial number are built. neither progress in battery technology nor consumer demand for evs has materialized the way that many had hoped a few years ago. in 1999, honda discontinued its ev plus model. a year later, general motors stopped building the ev1. gm has since decided not to renew the cars' three-year leases when they expire. chrysler's epic electric minivan, ford's ranger ev, nissan's altra ev, and other models are available only for demonstration or limited fleet use, without new production runs scheduled. in 2003, toyota pulled the plug on the rav4 ev sport utility as well.

    some consumers raise the question, "even though evs have zero tailpipe emissions, they use electricity from power plants, so don't they just cause pollution somewhere else?" yes, they do, but electric vehicles are less harmful to the environment than comparable gasoline vehicles for two main reasons.

    one is that a given amount of pollution from a power plant is likely to be much less damaging to health than a similar amount from a tailpipe. to make an analogy, imagine two sidewalk cafés, one at each end of a city block. someone is smoking a cigarette at a table at one of them. if you sit at the café at the far end of the block, you'll be less bothered by the smoke than if you are at a table in the same sidewalk café as the smoker. similarly, pollutants from vehicle tailpipes-emitted at ground level and directly in city streets-expose people to higher concentrations of noxious fumes than do power plants, which are generally in more remote locations and have stacks that allow the pollution to disperse before it reaches populated areas.

    the other reason is that real-world emissions from gasoline vehicles are still higher than the levels set by the tailpipe standards. this problem is not as bad as it once was, since epa has started requiring automakers to meet tougher tests of their cars' and light trucks' emission controls before selling them. battery electric vehicles avoid the emissions control malfunction and degradation problems that have plagued gasoline vehicles. by comparison, emissions from electric power plants have been more reliably regulated within their permitted levels.

    nevertheless, the relative environmental advantage of electrics is being lessened by ongoing reductions in pollution from gasoline vehicles. this progress is due to both better testing and automakers' growing experience with more effective emissions control technology. in performing research for aceee's green book® online, we examined the data on real-world emissions control performance. these data show that manufacturers are doing a better job of equipping their cars with controls that keep pollution low under a variety of driving conditions. the california air resources board (carb) and u.s. environmental protection agency (epa) check up on how well auto pollution controls are working in practice. such oversight pushes the car companies to fix flaws in their vehicles' emissions control equipment. tighter tailpipe standards begin taking effect this year and, once fully phased-in, will offer significantly greater environmental benefits. some of the cleanest vehicles of 2007—those meeting sulev ii and pzev standards—use emissions control technologies that will become commonplace over the coming years. the stringent standards, along with ongoing testing scrutiny by epa and carb, will further cut smog-causing pollution and save consumers money through avoided repair costs.

    in contrast to smog-causing pollution, the global warming pollution from any type of vehicle depends mainly on its fuel efficiency. carbon dioxide and other greenhouse gases are equally damaging no matter where they are emitted. an important advantage of electric vehicles is their potential for very efficient drivetrains. electric vehicle battery capabilities remain inherently limited and costs are likely to remain relatively high. in the long run, the electric drivetrain of choice may be the fuel cell, which chemically converts a fuel directly to electricity. for now, improvements in vehicle structures and gasoline drivetrain efficiency (and when available, the extra efficiency boost of hybrid drive) provide the best choices for affordable and practical designs that cause less global warming pollution.

    are there any federal or state incentives available for purchasing a green vehicle?

    as of january 1, 2006, many consumers purchasing hybrid-electric vehicles became eligible for a federal hybrid tax credit. aceee has computed estimates for the credit amounts, which vary by vehicle. the federal government's fueleconomy.gov web site provides additional tax incentive information about both hybrid-electric vehicles (hevs) and alternative fuel vehicles (afvs).

    who is the american council for an energy-efficient economy?

    aceee is a washington, d.c.-based independent, non-profit research group dedicated to advancing energy efficiency as a means of protecting the environment and strengthening the economy. read more about the organization at its website.

    i have additional questions about green vehicles. where should i direct them?

    please email any inquiries to greenercars@aceee.org.

    how can bookstores order aceee's green book®?

    contact chelsea green publishing at (800) 639-4099.

 

 
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