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"Green" is still a red-hot buzzword in the auto industry, with carmakers competing to showcase their commitment to fuel economy. It's not entirely altruistic; carmakers have to meet tougher fuel-economy standards between now and 2025. Each vehicle we spotlight is the least thirsty in its price category based on annual fuel cost. Most of the winners sport an alternative powertrain -- either gas-electric hybrid or all electric.

The annual fuel cost assumes 15,000 miles of combined city and highway driving each year and fuel prices of $3.70 a gallon for regular, $4 for premium and $4.15 for diesel. To be eligible, each most-fuel-efficient model must have been designated as a top 25 pick in its category, and no vehicle can win the award if another trim level of that model has won in a lower-price category.

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Toyota

MPG: City: 53; Hwy: 46

Sticker price: $19,925

Invoice price: NA

TrueCar national average price: NA

Resale value: 3-year: 64%; 5-year: 49%

The littlest Prius joined the Toyota family last year, with a strong family resemblance to the original Prius and a name that's practically synonymous with "green." Delivering 50 miles per gallon in combined city and highway driving, the Prius c boasts the best city fuel economy of any vehicle that doesn't plug in and the lowest price of entry into the hybrid market.

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Toyota

MPG: City: 51; Hwy: 48

Sticker price: $24,995

Invoice price: $23,543

TrueCar national average price: $23,888

Resale value: 3-year: 50%; 5-year: 39%

The best-selling hybrid worldwide, the Toyota Prius offers best-in-class fuel economy of 50 miles per gallon in combined city and highway driving. Touch-screen audio, Bluetooth and a USB plug are standard on all models. Step up to the Three trim level for more amenities -- Toyota's Entune multimedia system (featuring Bing, OpenTable and Pandora apps) and optional navigation, including a rearview camera.

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Smart

MPG: City: 122; Hwy: 93 (mpg equivalent)

Sticker price: $25,750

Invoice price: NA

TrueCar national average price: NA

Resale value: 3-year: NA; 5-year: NA

Coming this spring, the Smart fortwo Electric Drive will be the cheapest electric vehicle on the market. After a $7,500 federal tax credit, the cost is $18,250. A cabriolet model will be available for $28,750 ($21,250 after the credit). The tiny EV has the same interior and cargo space as the gas-engine model and fully charges in six hours with a 240-volt charger.

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Honda

MPG: City: 132; Hwy: 105 (mpg equivalent)

Sticker price: $36,625 (lease only, at $389 per month)

Invoice price: NA

TrueCar national average price: NA

Resale value: 3-year: NA; 5-year: NA

Honda's Fit EV slays the competition on "fueling up." The company claims the best range on a full charge of any electric vehicle on the market -- 132 miles for city driving (the Environmental Protection Agency tempers it to 82 miles for combined city and highway driving). Unfortunately, the zippy subcompact is available only for lease and only in two markets (Oregon and California); it expands to six East Coast markets this spring.

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Lexus

MPG: City: 40; Hwy: 39

Sticker price: $40,475

Invoice price: $37,958

TrueCar national average price: $39,347

Resale value: 3-year: 52%; 5-year: 40%

At long last, Lexus brings a hybrid powertrain to its popular ES midsize sedan. The electric motors and 2.5-liter four-cylinder deliver 200 total horsepower and 40 miles per gallon in combined city and highway driving. A rear spoiler and hidden exhaust are exclusive to the 300h, and both ES models are equipped with low-rolling-resistance tires.

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Lexus

MPG: City: 29; Hwy: 34

Sticker price: $59,845

Invoice price: $55,721

TrueCar national average price: $57,734

Resale value: 3-year: 51%; 5-year: 36%

Sprinting from 0 to 60 mph in 5.6 seconds doesn't sound like a feat of a typical hybrid -- but the average hybrid doesn't have 338 horsepower. The redesigned GS isn't an average Lexus, either. Its sporty handling, five adaptable driving modes (to conserve fuel or enhance drivability) and exterior styling leave snooze-inducing models of years past in the rearview mirror.

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Scion

MPG: City: 25; Hwy: 34

Sticker price: $26,055

Invoice price: $24,790

TrueCar national average price: $26,215

Resale value: 3-year: 49%; 5-year: 37%

Scion enters the enthusiast market and creates a new halo car for the brand with the 2013 FR-S. The rear-wheel-drive coupe sports a 2.0-liter, 200-horsepower engine that was a joint effort with Subaru. (The FR-S shares the engine and its platform with the Subaru BRZ; see the next slide.)

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Subaru

MPG: City: 25; Hwy: 34

Sticker price: $29,365

Invoice price: $27,891

TrueCar national average price: $29,638

Resale value: 3-year: 50%; 5-year: 38%

You wouldn't expect it, given the brand's largely utilitarian lineup, but Subaru's BRZ is downright sexy. Its lithe body will surprise those used to Subaru's staid designs; navigation, among other higher-end features, is standard. Because it shares its 200-hp engine and platform with the Scion FR-S, it shares its fuel economy. But in terms of quality -- from fit and finish to materials and standard features -- the Subie finishes first.

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Ford

MPG: City: 44; Hwy: 41

Sticker price: $33,745

Invoice price: $31,521

TrueCar national average price: $32,927

Resale value: 3-year: 47%; 5-year: 35%

Boasting a mile-per-gallon equivalent of 100 mpg -- better than Toyota's Prius plug-in -- the C-Max Energi, which is Ford's first plug-in, also has a longer range than Chevrolet's Volt (Ford claims a 500-mile range). SYNC with MyFord Touch comes standard, and a mobile app lets you monitor and schedule charging remotely.

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Nissan

MPG: City: 19; Hwy: 25

Sticker price: $26,815

Invoice price: $25,047

TrueCar national average price: $25,354

Resale value: 3-year: 47%; 5-year: 36%

The Quest edges out the handful of other minivans on offer for best fuel economy, and it is made with family comfort in mind. Second-row captain's chairs recline and slide fore and aft, 12 cup holders are standard, and even the third row reclines. Higher trim levels include a conversation mirror, to aid those with children in the rear, and Nissan's Around View monitor, which gives better views for navigating in and out of tight parking spots.

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Nissan

MPG: City: 27; Hwy: 32

Sticker price: $20,780

Invoice price: $19,850

TrueCar national average price: $20,580

Resale value: 3-year: 47%; 5-year: 36%

Nissan's subcompact crossover channels sports cars with a lowered driving position, dynamic handling and bold styling. Under its hood is a 1.6-liter turbocharged engine that puts out 188 horses and delivers 29 mpg in combined city and highway driving.

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Toyota

MPG: City: 28; Hwy: 28

Sticker price: $40,815

Invoice price: $37,617

TrueCar national average price: $39,256

Resale value: 3-year: 50%; 5-year: 39%

The hybrid variant of Toyota's popular Highlander pairs a 3.5-liter V6 with an electric motor to generate 280 horsepower. An additional electric motor provides power to the rear wheels and supplies extra torque when needed for the intelligent four-wheel-drive system. An EV switch in the console allows you to drive in electric-only mode at low speeds or in stop-and-go traffic.

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Cadillac

MPG: City: 20; Hwy: 23

Sticker price: $74,845

Invoice price: $70,045

TrueCar national average price: $72,870

Resale value: 3-year: 49%; 5-year: 34%

Though the Escalade is typically associated with conspicuous consumption, the hybrid version is as "green" as any truck-based SUV gets. It delivers 50% better city fuel economy than the gas-engine model, with a combined city/highway rating of 21 miles per gallon.

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Chevrolet

MPG: City: 20; Hwy: 23

Sticker price: $54,040

Invoice price: $51,123

TrueCar national average price: $49,656

Resale value: 3-year: 48%; 5-year: 33%

The Tahoe Hybrid shares a platform and powertrain with Caddy's hybrid (as well as the GMC Yukon Hybrid) and thus shares fuel-economy honors. Low-rolling-resistance tires, regenerative braking and auto-stop mode, which allows the gas engine to shut down at speeds below 30 mph, help it boost city fuel economy. The Tahoe seats eight, uses regular gas and tows 6,200 pounds on 2WD models.

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GMC

MPG: City: 20; Hwy: 23

Sticker price: $54,565

Invoice price: $51,619

TrueCar national average price: $50,085

Resale value: 3-year: 51%, 5-year: 36%

Of the SUV fuel-economy trifecta, GMC's Yukon Hybrid is the best value. Pricing is similar to the Chevy Tahoe Hybrid, and interior features are the same, but resale values are higher. The available Denali trim features 22-inch chrome wheels, a power liftgate, a rearview camera and park assist.

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