The 2015 Hyundai Sonata Eco is the Korean maker's most fuel-efficient mid-size sedan that doesn't use a hybrid powertrain.

And it highlights the two parallel paths that automakers are taking as they work to boost gas mileage ratings to meet steadily rising corporate average fuel economy rules.

The Sonata Eco uses a smaller gasoline engine, a different transmission, and some other modifications to deliver the highest ratings of any non-hybrid Sonata.

DON'T MISS: 2015 Hyundai Sonata Eco: Quick Drive Of Higher-Gas Mileage Small Turbo Four

Unlike the conventional gasoline Sonata, with its 2.0-liter engine, the Sonata Eco is powered by a turbocharged 1.6-liter four that produces 178 horsepower and 195 lb-ft of torque.

The Eco is also the sole Sonata to use Hyundai's own seven-speed dual-clutch transmission, rather than the more conventional six-speed automatic. It's also fitted with a high final-drive ratio.

The 2015 Sonata Eco is EPA-rated at 32 mpg combined (28 mpg city, 38 mpg highway).

2015 Hyundai Sonata Hybrid 4-door Sedan Limited Dashboard

2015 Hyundai Sonata Hybrid 4-door Sedan Limited Dashboard

That compares to the conceptually similar 2015 Ford Fusion 1.5 EcoBoost, which comes with ratings of 29 mpg combined (25 mpg city, 37 mpg highway), but uses a conventional six-sped automatic transmission.

We had driven the Sonata Eco briefly last October, during testing for our Green Car Reports 2015 Best Car To Buy award nominees.

But quick loops through the twisty Malibu canyons above Los Angeles are hardly representative of how most buyers will use a car like this.

ALSO SEE: 2015 Hyundai Sonata Eco: Best Car To Buy 2015 Nominee

So, last December, we got a chance to test its real-world fuel economy on a long Northeastern road trip--although it had a higher proportion of highway miles than many Sonatas may see.

Still, over 540 miles, the car's trip computer told us we had achieved a rating of 33.2 miles per gallon overall.

That's about what we expected to get from this particular mid-size sedan with two occupants and their luggage (especially in cold winter weather that required constant use of the heater and fans).

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

[EDITOR'S NOTE: Alert readers will notice that, with one exception, the photos accompanying this article were taken in Los Angeles--which is to say, they're not scenes of Vermont or any of the other scenic areas we traveled through. Chalk it up to a technical error.]

Other notes from our four days with the Sonata Eco:

  • This Sonata's transmission is one of the softer dual-clutch units we've driven, though we experienced occasional lurching in quick on/off power applications
  • For low-rolling-resistance tires, the ride was fairly soft--a good thing--though like many harder tires, they could get quite noisy on certain rough surfaces
  • The Sonata Eco's power steering was among the numbest we've driven lately, requiring many small corrections to stay on center at highway speeds
  • The relatively high fuel economy ensured a long distance between refills; we got more than 500 miles on our first tank of gas
  • Kudos to the sedan designers who kept the rear seat high enough that a 5-foot-tall passenger could see out the rear side windows; that's not always the case these days

Overall, the 2015 Hyundai Sonata Eco has all the benefits and virtues of a big mid-size sedan.

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

Competitors include the Chevrolet Malibu (redesigned for 2016), Chrysler 200, Ford Fusion, Honda Accord, Kia Optima, Nissan Altima, and Toyota Camry.

While we weren't wild about a couple of the driving characteristics, we could definitely live with this powertrain for what we'd expect to be combined fuel economy of 30 mpg or better over the long run.

MORE: 2015 Hyundai Sonata - full review

Our Hyundai Sonata Eco test car carried a base price of $23, 275--about $2,000 higher than the least expensive 2015 Sonata.

A tech package added $4,100, consisting of a navigation system with an 8-inch touchscreen display, blind-spot detection with rear cross-traffic alert, leather upholstery with heated front seats, dual-zone temperature control, and a host of smaller upgrades and trim items.

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

2015 Hyundai Sonata Eco, Malibu, California, Oct 2014

Carpeted floor mats, a cargo net, a cargo tray, a first-aid kit, and wheel locks together added $375 more.

With a mandatory $810 "inland freight and handling" charge (aka destination fee), the bottom line came to $28,560.


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