Plug-in cars may get a lot of attention, but improving the efficiency of big trucks can have a huge effect on reducing overall emissions--and owners' fuel bills as well.

The 2014 Ram 1500 EcoDiesel attempts to tackle the problem of full-size pickup-truck fuel economy with something not seen in any other current production half-ton truck: a diesel engine.

The EcoDiesel has already achieved impressive EPA-rated fuel economy, but has it retained its essential truck-ness? Will the downsized engine sacrifice the capability buyers expect from their full-size trucks?

DON'T MISS: Why Green Car Reports Writes About Full-Size Pickup Trucks

We climbed into the cab of a 2014 Ram 1500 EcoDiesel in New York’s Bear Mountain State Park to find out.

The 3.0-liter EcoDiesel V-6 is the same one used in the Jeep Grand Cherokee EcoDiesel, and it’s even fitted to the Maserati Ghibli and Quattroporte luxury sedans--in Europe.

The engine produces 240 horsepower and 420 pound-feet of torque. An eight-speed automatic transmission is the only option.

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

While underway, the EcoDiesel emits a loud clatter that’s definitely characteristic of a big truck, but the relatively-modest power output won’t inspire delusions of 18-wheeler grandeur.

Overall, power delivery is adequate, but the throttle requires a little extra prodding on hills to maintain momentum.

That’s not much of a compromise, though, considering the EcoDiesel’s fuel-economy ratings.

ALSO SEE: New Diesel SUVs & Crossovers: Jeep, Audi, Mercedes Fuel Economy Tested

The EPA rates the 2014 Ram 1500 EcoDiesel at 23 mpg combined (20 mpg city, 28 mpg highway) for rear-wheel drive models.

Our four-wheel drive test vehicle loses 1 mpg in each category, for a rating of 22 mpg combined (19 mpg city, 27 mpg highway).

2014 Ram 1500 EcoDiesel

2014 Ram 1500 EcoDiesel

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

In both cases, the EcoDiesel bests the fuel economy of the most-efficient full-size pickups from Ford and General Motors.

It’s also worth noting that diesels often exceed their EPA highway mileage ratings in real-world driving.

However, we weren’t able to properly test these figures, as our drive covered only a few miles with a nearly-full tank.

The truck itself rode quite well--likely thanks to the (optional) four-corner air suspension--while the steering was fairly quick for a full-size truck.

The upscale leather-lined interior was marred by a few gaudy touches--including a plastic-looking wood-trimmed steering wheel and massive “Limited” badge on the center bin lid--but seemed well-built, right down to the detailed stitching on the door panels.

MORE: 2014 Jeep Grand Cherokee EcoDiesel: Diesel SUV Fuel Economy Tested

Questionable stylistic touches didn't lessen the interior's functionality, either.

The automatic transmission’s rotary shifter knob makes plenty of room for storage and buttons for Chrysler’s UConnect system, which displays audio and navigation functions on an 8.4-inch center-stack touch screen.

Our top-of-the-line Ram 1500 Laramie Limited Edition Crew Cab 4x4 has a starting price of $49,330.

The EcoDiesel engine option added $2,850 to that, and includes an 800-amp battery, the necessary urea exhaust-aftertreatment system, heavy-duty cooling, and a 26-gallon fuel tank.

On top of that, the $2,495 Customer Preferred Package added the air suspension, body-color bumpers, and heated and ventilated front seats with 10-way power adjustment for the driver, among other features.

Other options included extra-large mirrors and brake control for towing ($330), a sunroof ($995), RamBox lockable storage bins in the bed ($1,295) and--surprising in thus age of digital music--a $195 single-disc remote CD player.

With the mandatory $1,195 destination charge, the grand total was $59,010.

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