How do you make a full-size pickup truck more fuel-efficient? Fitting in a smaller diesel engine seems to be working for Ram.

The 2014 Ram 1500 EcoDiesel achieved an EPA fuel-economy rating of 23 mpg combined for rear-wheel drive models.

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

That represents a city rating of 20 mpg and a highway number of 28 mpg--which Ram says is the best ever for a full-size pickup in EPA testing.

Four-wheel drive models are rated at 22 mpg combined (19 mpg city, 27 mpg highway).

2014 Ram 1500 EcoDiesel

2014 Ram 1500 EcoDiesel

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.

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

The EcoDiesel's fuel economy bests that of a 2014 Ford F-150 equipped with the 3.5-liter EcoBoost V-6--which produces 365 hp and 420 lb-ft--and obligatory six-speed automatic transmission.

With rear-wheel drive, the F-150 EcoBoost is rated at 18 mpg combined (16 mpg city, 22 mpg highway). It loses one mpg in each category with four-wheel drive.

However, this model will soon be replaced by the 2015 F-150, which features a lighter aluminum body and an available 2.7-liter EcoBoost V-6 with Auto Start-Stop.

MORE: Why Green Car Reports Writes About Full-Size Pickup Trucks

The 2014 Ram 1500 EcoDiesel also beats the most fuel-efficient full-size General Motors pickup in fuel economy.

The 2014 Chevrolet Silverado C15 is equipped with a 4.3-liter V-6 producing 285 hp and 305 lb-ft. With the obligatory six-speed automatic and rear-wheel drive, the Chevy is rated at 20 mpg combined (18 mpg city, 24 mpg highway).

The four-wheel drive Silverado K15 loses 1 mpg in the city and combined categories, and 2 mpg in the highway category.


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