Cruze Turbo is fossil-fuel mileage champ.

• Author: Ulrich, Lawrence
• Position: Cars

Byline: Lawrence Ulrich

Despite several do-gooder attempts, from the EV1 electric car to the Volt plug-in hybrid, General Motors has not always been viewed as a particularly green automaker.

Pumping out Hummers and other greed-is-good models during the SUV glory years had something to do with that. But the post-bankruptcy GM is not just getting with the program, it is stamping its name above the fold.

GM's Chevrolet Spark EV is the most efficient electric vehicle sold in America (though only in California and Oregon for the time being) with a federal gasoline-equivalent rating of 119 miles per gallon.

Now the Chevy Cruze, already among the highest-mileage compact sedans running on gasoline, raises its bar: with a rating of 46 mpg, the 2014 Cruze Turbo Diesel achieves the best highway mileage of any new nonhybrid car in America.

The Cruze also becomes the first Chevy diesel since the 1986 Chevette. Weighing the Cruze against that Chevette -- the latter's engine as pitiful as the car itself -- shows how far the technology has come. It also illustrates how GM is building world-competitive small cars after decades of bumbling indifference.

GM has sold more than 2 million Cruzes globally since the car's overseas debut in 2009, including more than 125,000 with diesel engines. Popular and right-sized, with some of the lowest warranty costs of any Chevy, the Cruze was GM's ideal choice to reintroduce a diesel to America, said Josh Tavel, the vehicle performance manager for GM's small cars.

GM prepped this Ohio-built Cruze with myriad changes to both the gasoline version -- including a Cruze Eco that hits 42 mpg on the highway, albeit with a manual transmission -- and international diesel models. The idea was to banish any trace of old-school diesel noise...