Hybrids and fuel-sipping small cars may get a lot of attention, but improving the gas mileage of pickup trucks can have a huge impact.

That's why the 2014 Ram 1500 EcoDiesel is major news for pickup buyers.

And while EPA fuel economy ratings aren't available yet, this diesel light-duty truck returned 28 mpg highway in a recent Motor Trend test.

MORE: 2014 Pickup Truck Gas Mileage: Ford Vs Chevy Vs Ram, Who's Best?

The 3.0-liter EcoDiesel V-6 is the same one used in the Jeep Grand Cherokee EcoDiesel, and is the only diesel engine offered in a half-ton truck this year. It produces 240 horsepower and 420 pound-feet of torque.

Even if the EPA rating varies from that 28-mpg highway figure, drivers may be able to replicate it in the real world. Many diesels do significantly better than their EPA highway ratings.

2014 Ram 1500 EcoDiesel

2014 Ram 1500 EcoDiesel

The car magazine's complete numbers were: 22 mpg combined (18 mpg city, 28 mpg highway) for the rear-wheel drive model, and 19 mpg combined (16 mpg city, 23 mpg highway) for the four-wheel drive model.

Both trucks were equipped with an eight-speed automatic transmission, the sole option.

That's compared to 20 mpg combined (17 mpg city, 25 mpg highway) for a rear-wheel drive Ram 1500 equipped with the 3.6-liter Pentastar V-6 (305 hp, 269 lb-ft) and eight-speed automatic, and 19 mpg combined (16 mpg city, 23 mpg highway) with four-wheel drive.

Buyers can also specify a 5.7-liter Hemi V-8, with 395 hp, 410 lb-ft, and a choice of six- or eight-speed automatics.

The six-speed Hemi returns 16 mpg combined (14 mpg city, 20 mpg highway) with rear-wheel drive and 15 mpg combined (13 mpg city, 19 mpg highway) with four-wheel drive.

With the eight speed, the numbers are 17 mpg combined (15 mpg city, 22 mpg highway) for rear-wheel drive, and 17 mpg combined (15 mpg city, 21 mpg highway) with four-wheel drive.

So far, the Ram EcoDiesel's closest Detroit rival is the rear-wheel drive 2014 Chevrolet Silverado C15, which is rated at 20 mpg combined (18 mpg city, 24 mpg highway). The Chevy has a 4.3-liter V-6 with 285 hp, 305 lb-ft, and a six-speed automatic.

The four-wheel drive Silverado K15 loses one mpg in the city and combined categories, and two mpg in the highway category.

The 2014 Ford F-150's 3.5-liter EcoBoost V-6 is rated at 18 mpg combined (16 mpg city, 22 mpg highway) with rear-wheel drive and the obligatory six-speed automatic, and loses one mpg in each category with four-wheel drive. It has 365 hp and 420 lb-ft.

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