Dear Lazy Environmentalist,

Can I afford an eco-friendly car?

When it comes to picking a vehicle, the smart choice for the planet is very often the smart choice for your wallet. That’s because the more expensive your new car, the worse it typically performs on gas mileage. This means you pay more at the pump, and your car emits more greenhouse gas emissions into the atmosphere. Conversely, the most affordable cars on the road almost always cost the least to operate, get the best fuel economy and release the fewest greenhouse gases.

So it stands to reason that hip, green automobile affordability starts with the nimble lineup of sub-$15,000 hatchbacks gaining popularity across the United States. None is more nimble and hip than the Honda Fit (starting msrp: $13,950; combined mpg 31), a new generation of mega-versatile hatchback that delivers high gas mileage in a package that combines style and smarts. Honda placed the gas tank under the front passenger seat, which allows the back seats to fold flush to the floor. This gives the streamlined caravan a surprisingly roomy cargo space and opens it up to multiple passenger/storage configurations. Kids, camping gear, groceries, pets — they’ll all fit in the Fit (sorry, couldn’t resist). Honda has entered the next level of affordable design with a car that’s earth-, family-, and even iPod-friendly—just plug it right into the stereo system. But don’t take it from me. Motor Trend magazine calls the Fit "the right choice for the enthusiast who wants a car that handles twisties as well as it does chores, saves gas and eases your budget."

A flashier newcomer 

A relative newcomer to the hatchback scene is a car so unique it almost defies categorization. Building upon the success of the MINI Cooper (starting msrp: $18,050; combined mpg: 32) MINI has introduced the MINI Clubman (starting msrp: $19,950; combined mpg: 32), an equally fun ride in a body that accommodates more passengers and more stuff. The Clubman is fast. The Clubman is cool. The Clubman also has a unique club door. In addition to two regular front doors, the car has one narrow door on the right side that’s used as a backseat entrance. The Clubman’s trunk is also original, with two barn doors that open outward to the sides.

Never a parking spot too small

Another option that skimps on gas but not on pleasure is the Smart Car. The mini vehicles arrived in the States in 2008 to offer commuters yet another fun, affordable, fuel-efficient option. The Smart Fortwo (starting msrp: $11,590; combined mpg: 36) comes in both hardtop and convertible models, both of which deliver unprecedented levels of joy each time you slide the minute vehicle into the narrowest of parking spots. Originally developed in Europe as a joint venture between Swatch (yup, the watch company) and Mercedes-Benz, the Smart Fortwo’s colorful, attractive design reflects its heritage. And thanks to German engineering, the Fortwo’s small engine can rev up to 90 miles per hour, so even if highway driving is part of your daily commute, this little car will get you where you want to go.

Righteous hatchbacks achieve top-flight fuel economy in two ways. First, they trade excessive power for supreme efficiency (while they’ve got above average pick-up, they’re probably not the best for street-legal drag racing — unless souped-up, of course). Second, these cars are lightweight. They’re still safe, but weigh about 2,000 pounds less than beefier sedans and station wagons. Remember what it felt like when the hefty class bully jumped on your back for a piggyback ride? That’s how a car engine feels when lurching forward under the weight of the typical luxury sedan or station wagon. Car engines propelling heavier loads expend more energy, consume more fuel, and release more greenhouse gases than when tucked inside nimble, lightweight, lower-priced vehicles.

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Excerpted from Josh Dorfman's latest book, The Lazy Environmentalist on a Budget.

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Photo: David Zalubowski/AP