DETROIT -- General Motors said the 2014 Chevrolet Cruze Turbo Diesel will deliver an estimated 46 miles per gallon on the highway, besting the company's initial target by four mpg.
The estimate is also good enough to top the rival 2013 Volkswagen Jetta diesel, which achieves 42 mpg on the highway.
Based on the estimated mpg for highway, it will be the most fuel efficient non-hybrid passenger car in America, according to GM.
The Cruze's 2-liter turbo diesel engine produces 148 horsepower, compared with 140 hp for the Jetta diesel.
After its February introduction at the Chicago auto show, GM engineers continued to make adjustments to the Cruze diesel to improve its fuel economy.
It emits 90 percent less nitrogen oxide and particulate emissions than earlier diesel models, GM said.
"We were still testing at the time, but wanted to be clear that we would be at or better than Jetta," a GM spokeswoman said. "The engineering team did a lot of incremental changes to the Cruze diesel from the Eco model to gain efficiency."
The Cruze diesel will be GM's first diesel car sold in the United States since the 1980s.
It is also a bellwether for diesel demand in the country as more automakers weigh the technology to comply with stricter U.S. fuel economy rules.
Volkswagen is the only nonluxury brand now selling diesels and dominates the U.S. market with its TDI offerings in the Jetta, Passat, Beetle and Golf.
Last year, 20 percent of U.S. Jetta sales were diesel versions.
The starting price for the Cruze diesel is $25,695, including shipping. It will go on sale in select U.S. cities this spring, and nationwide and in Canada in the early fall, GM said.
Chevy Cruze sales have slipped 2 percent this year through March to 55,731 and GM is counting on the diesel variant to spark new interest in the compact sedan.
Since its mid-2010 launch, Cruze sales have eclipsed 2 million units globally, with more than 33,000 of them powered by diesel engines.
Gary Altman, chief engineer for the Cruze Diesel, said: "We harnessed generations of diesel expertise to adapt our world-class global engine for the North American market."