The third of our five nominees for Green Car Reports' 2015 Best Car To Buy award is the new 2015 Hyundai Sonata Eco, the most fuel-efficient non-hybrid version of the Korean maker's mid-size sedan.

This new-for-2015 version of the Sonata is the sole model to use a turbocharged 1.6-liter engine, in this case producing 178 horsepower and 195 lb-ft of torque.

DON'T MISS: Green Car Reports' 2015 Best Car To Buy: The Nominees (Video)

It's also the only one that offers Hyundai's own seven-speed dual-clutch transmission, which replapces than the conventional six-speed automatic used in other gasoline Sonatas, along with a higher final-drive ratio.

The result is gas mileages ratings of 32 mpg combined (28 mpg city, 38 mpg highway).

2015 Hyundai Sonata Dashboard

2015 Hyundai Sonata Dashboard

Not so many years ago, a 32-mpg combined rating for a mid-size sedan might have been province only of more expensive hybrid versions--which now top out at roughly 40 mpg combined, meaning savings of about half a gallon of gasoline every 100 miles.

The 2015 Sonata Eco is also Hyundai's first foray into matching its lineup head-to-head with the maker offering the greatest array of powertrains in a mid-size sedan.

That would be Ford, which this year offers two different turbocharged EcoBoost engines (of 1.5 and 2.0 liters, respectively) and a low-volume 2.5-liter conventional gasoline four, along with both a hybrid and a plug-in hybrid Energi model in its 2015 Fusion sedan range.

MORE: 2015 Hyundai Sonata Eco: Quick Drive Of Higher-Gas Mileage Small Turbo Four

Hyundai doesn't have the plug-in hybrid yet, although that's coming, but the Sonata Eco actually bests the 1.5-liter Fusion EcoBoost, which is rated 3 mpg lower, at 29 mpg combined (25 mpg city, 37 mpg highway).

In a brief drive of the Sonata Eco, we weren't able to test its real-world gas mileage under conventional uses.

Instead, we spent a couple of hours snaking through the hills and canyons outside Malibu, California.

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

We found the Sonata Eco to offer all the virtues of the standard, new-for-2015 Sonata model (although Sonata Hybrids are carryovers for one year), though high gearing and turbo lag combined to delay acceleration for a second or two.

On the other hand, the only DCT offered in the Sonata range behaved more like an automatic, with soft shifts and even occasional delays to buffer what in some cars can be abrupt shifts from a fast automated manual gearbox.

ALSO SEE: Ford Fusion Vs Hyundai Sonata: Mid-Size Sedan Gas Mileage Comparison

With higher gas mileage than the base Sonata and a base price considerably lower than the Sonata Hybrid, the Sonata Eco fleshes out the all-new 2015 Sonata lineup.

And it marks another step in Hyundai's commitment to competing very, very aggressively against Toyota, Honda, Ford, and others for the hearts and minds of mid-size sedan buyers.

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