Adapted from a list compiled by the American Council for an Energy-Efficient Economy of the greenest vehicles of 2009, which combined both the gas mileage and environmental effects of the vehicles. Summary overview by noted automotive information website Edmunds.com.

1) The Honda Civic GX – Natural Gas, and Honda Civic Hybrid

The Honda Civic GX natural-gas powered vehicle.

GX – Natural Gas Engine
MPG: 24 City; 36 Hwy
MSRP: $25,190

Hybrid
MPG: 40 City; 45 Hwy
MSRP $23,650

Review:

Comfortable, smartly designed and available in a wide array of configurations, the 2009 Honda Civic sets the bar for the small-car segment.

Pros

Wide-ranging engine lineup offers both fuel efficiency and performance, roomy and refined interior, strong crash test scores, available as a sedan or coupe.

Cons

Controversial gauge cluster design, Bluetooth and stability control only available on upper trims, slow acceleration times of Hybrid and GX models.

What’s New for 2009

Marking the changes for the 2009 Honda Civic are a slight nose and tail job, new wheel designs, a pair of new trim levels (LX-S and DX Value Package) and a number of high-tech enhancements (including Bluetooth availability and a USB audio input).

2) Toyota Prius

MPG: 48 City; 45 Hwy

MSRP: $22,000

Review:

No car boasts a better blend of fuel and space-efficiency than the 2009 Toyota Prius.

Pros

Outstanding fuel economy, generous amount of interior space, easy to maneuver in tight spaces, high-tech and luxury goodies available.

Cons

Less powerful and agile than other midsize sedans, uncomfortable for 6-foot-plus drivers, a few disappointing interior plastics.

What’s New for 2009

There are no significant changes for the 2009 Toyota Prius.

3) Smart Fortwo Convertible

MPG: 33 City; 41 Hwy

MSRP: $16,990

Review:

The 2009 Smart Fortwo is a great city car, but its high price, herky-jerky transmission and unpleasant highway ride reduce its appeal when compared to other compacts.

Pros

Fits in spaces others cannot, zippy around-town handling, surprisingly accommodating interior, high fuel economy, attention-getting style.

Cons

Herky-jerky automanual transmission, expensive compared to larger subcompact cars, awkward floor-mounted brake pedal, ill-suited for highway travel.

What’s New for 2009

The 2009 Smart Fortwo returns with the introduction of a sportier trim level from German tuner Brabus. Minor changes to the returning models include flexible door storage nets.

4) Toyota Yaris

MPG: 29 City; 36 Hwy

MSRP: $12,965

Review:

The 2009 Toyota Yaris boasts a variety of body styles and a solid track record for reliability, but there are better choices for an economy car.

Pros

Very fuel-efficient, comfortable ride, handsome interior, multiple body styles, hatchback’s available multifunction rear seat.

Cons

Acceleration-sapping automatic transmission, awkward seating position, centrally placed gauges.

What’s New for 2009

For 2009, the Toyota Yaris becomes safer via standard side curtain airbags and antilock brakes. This year also brings a new addition to the lineup: a four-door hatchback.

5) Nissan Altima Hybrid

MPG: 35 City; 33 Hwy

MSRP: $26,650

Review:

The 2009 Nissan Altima Hybrid is an excellent choice for drivers who want a little fun between point A and point B. Too bad it’s only sold in the eight states that have adopted California’s emissions standards.

Pros

Excellent fuel economy, sporty handling, precise steering, top-notch interior materials, high crash test scores.

Cons

Can only be obtained in eight states, options are only offered in expensive packages, so-so backseat comfort.

What’s New for 2009

The 2009 Nissan Altima Hybrid remains unchanged from the previous year, except for standard automatic door locks and four more exterior color choices.