LAST week's column explained why one's choice of vehicle is one of the largest decisions most of us make regarding our impact on the Chesapeake Bay, the global environment and human health.
If America's SUV-heavy vehicle fleet was a nation unto itself, it would produce more carbon dioxide than the total from all but three other countries.
Similarly, the fleet is a major contributor to the 304 million pounds a year of nitrogen that is the bay's worst pollutant.
Meanwhile, average auto mileage is lower than any time since 1980 - slipping by two miles per gallon since 1988.
With the U.S. Senate, including five of the bay region's six senators, refusing this month to push automakers toward higher overall fuel efficiency, improvements are more often being left to individual choice.
The good news is that no matter what you feel you need to drive, you can make significantly greener, or environmentally friendly, choices.
Start any new car purchase by investing $8.95 in the recently released edition of the Green Book, an environmental guide to all 2002 cars and trucks (get it online for the same price).
Published by the nonprofit American Council for an Energy-Efficient Economy, it's the equivalent of the Kelley Blue Book guide to auto prices - it's also a readable, no-nonsense primer on how car choice affects the environment.
The Green Book assigns each make and model an overall score that factors in its fuel economy and its effects on human health (as from smog) and the environment.
These composite "green scores" on a scale of zero to 100 range as low as 10 (for your basic Lamborghini V-12 or the Dodge Ram 2500 V-8, four-wheel drive pickup), to a peak score of 57 for Honda's innovative gas-electric hybrid, the Insight, which gets an honest 56 miles per gallon and emits about 10 percent of the bay-polluting nitrogen that most vehicles on the road emit.
The differences in annual environmental impacts between classes of vehicle are significant:
A typical big SUV will produce 40 pounds of nitrogen and 17 tons of carbon dioxide a year.
A moderately sized SUV, such as the Ford Explorer, cuts that to 31 pounds and 15 tons.
A midsize station wagon, such as the Ford Taurus, further reduces one's impact - to 22 pounds and 12 tons.
A compact car, such as Volkswagen's Jetta station wagon, comes in at 21 pounds of nitrogen and 11 tons of carbon dioxide.
But even within categories of vehicle, differences give a careful shopper real choices to go greener. Minivans, for example, range from green ratings of 16 to 18 for Chevy's Astro and GMC's Safari, up to 25 for a Dodge Caravan, Oldsmobile Silhouette and Pontiac Montana.
Among sports cars, the BMW Z3 Roadster gets a 30 compared with a 24 to 26 for a Porsche Boxster.
Among subcompacts, Honda's Civic HX gets a 41 to 42, compared with 21 for the Jaguar XKR. Admittedly, a Civic is not a Jag, but consider, perhaps, Mercedes' subcompact CLK 320, with a green score of 27, as an alternative.
One note of interest among the smaller vehicles: Volkswagen makes a very nice diesel option with an impressive 49 highway miles per gallon, but its green score is low (24) as with all diesels.
Why? The Green Book's authors say diesel engines emit a lot more fine particles than gasoline engines do. These particles, which lodge in the lungs, are a leading and well-documented cause of premature deaths from air pollution.
In midsize autos, the heart of the passenger car market, choices range from Ford's Focus, 33 to 35, to Honda's Accord, 30 to 32, and Toyota's Camry, 33, down through the Lexus ES300 at 29, to the Lincoln LS and Mercedes E55 AMG at 23.
Pickups and SUVs account for more than half of all new vehicles sold in America. If a compact pickup will satisfy your need to sit up higher and haul stuff, you can be somewhat green with a Ford Ranger, Chevy S10 or Mazda B2300, all of which have scores ranging from 26 to 29.
Big pickups are some of the worst-scoring vehicles available, rating as low as 10 to 12, but even here you can get a Ford F150 or Toyota Tundra with a score as high as 20 or 21. A tip: Think about whether you really need the V-8 or the four-wheel drive.
Similarly, among SUVs, many of the smaller ones, such as Honda's CR-V and Mazda's new Tribute, score 29. Even among the heavyweights, models such as Toyota's V-8, four-wheel drive Sequoia, rate 50 percent greener than the worst of the lot.
With information like the Green Book available, there's no excuse for not choosing greener, no matter what you drive. Get it at www.aceee.org, by sending e-mail to email@example.com, or by calling 202-429-0063. Give a copy to your library.
Greenest and Meanest Wheels of 2002
A selection of most and least environmentally friendly vehicles, as ranked by the American Council for an Energy-Efficient Economy.
Make, model...Fuel...City/highway...Green score
Honda Civic GX...CNG...30/34...52
Dodge Ram PU 2500...Gasoline...11/15...10
Chevrolet Suburban K2500...Gasoline...11/15...10
GMC Yukon XL K2500...Gasoline...12/15...10
Mercedes Benz G500...Gasoline...12/14...11
Source: ACEEE's Green Book Web site