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 S.U.V. glory years had something to do with that. But the post-bankruptcy G.M. is not just getting with the program, it is stamping its name above the fold.
G.M.'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 m.p.g., 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 G.M. is building world-competitive small cars after decades of bumbling indifference.
G.M. has sold more than two 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 G.M.'s ideal choice to reintroduce a diesel to America, said Josh Tavel, the vehicle performance manager for G.M.'s small cars.
G.M. prepped this Ohio-built Cruze with myriad changes to both the gasoline version -- including a Cruze Eco that hits 42 m.p.g. on the highway, albeit with a manual transmission -- and international diesel models. The idea was to banish any trace of old-school diesel noise, smell and sluggishness.
"We all know what the old diesel myths are, so we really looked to dispel them," Mr. Tavel said.
The 2-liter engine, developed by G.M.'s European division, Opel, injects fuel as many as five times per engine cycle. Engineers tinkered with 33,000 calibration parameters for the diesel, compared with some 12,000 to 17,000 for G.M.'s typical gasoline engines.
The resulting turbocharged engine is more powerful and slightly more efficient than VW's same-size diesel in the Jetta TDI sedan. The Chevy's 151 horsepower and 264 pound-feet of torque compare with 140 and 236 for the Jetta. On fuel economy, the Chevy takes the highway crown, at a rated 46 m.p.g. versus the Jetta's 42. But the Jetta's city rating of 30 m.p.g. beats the Cruze's by 3 m.p.g.
The Cruze is quicker off the line than the VW, burbling to 60 m.p.h. in a reasonable 8.6 seconds. And like just about every modern diesel, the Cruze's bounteous torque makes the car feel surprisingly muscular in real-world driving. With 15.6 gallons of fuel aboard, the Chevy can cover nearly 720 miles to a tank, enough to drive from Detroit to New York with nearly 100 miles to spare.
Like many diesels in the United States, which has far stricter regulations on smog-forming nitrogen oxides than Europe, the Chevy carries a small onboard tank of urea that's injected into the exhaust stream to neutralize pollution.
VW wins that battle; its 4-cylinder diesels meet 50-state emissions rules with no need for a urea tank. Chevy owners must refill theirs every 10,000 to 15,000 miles.
While the Cruze's engine is already quieter than rackety old-school diesels, the car adopted extra sound padding from its pricier cousin, the Buick Verano. A structural brace on the engine cradle counteracts vibration from the higher idle speed.
The gasoline Cruze is already among the most hushed cars in its class. But in some situations, Chevy says the diesel is measurably quieter than the gas engine.
The engine was also retuned to optimize power and efficiency at the lower engine speeds where Americans tend to drive. All six gears of the automatic transmission (no stick shift is offered) were remapped.
To further bolster mileage, Chevy adopted aerodynamic aids from the gas-powered Cruze Eco, including front grille shutters that automatically adjust to reduce airflow and cut drag at higher speeds.
"We spent a lot of third-shift nights in the wind tunnel, getting air through the radiator as efficiently as possible," Mr. Tavel said.
Underbody panels further help to smooth airflow, along with front deflectors that reduce turbulence around the wheel wells and the spinning tires.
For bitter northern climates, the Cruze Diesel sold here gets more advanced glow plugs to ensure, G.M. promises, cold starts at temperatures as low as 40 degrees below zero. And the American version adopts larger brake rotors for the front and the rear.
In case any sensitive nose could detect a residual trace of diesel's telltale odor, Chevy added a charcoal filter to the climate system.
I've beaten the E.P.A. economy estimates with most of the diesels currently on sale, and I did so again with the Cruze. Over a 4.5-hour drive to Monticello, N.Y., and back to Brooklyn, I managed 49 m.p.g. on the highway portion -- about what I've achieved in VW diesels.
That's impressive, though the benefits are less compelling for drivers who often cool their heels in traffic. Hybrids still trump the efficiency of diesels in city and suburban driving -- though they are invariably less fun and satisfying to drive.
As with the gas model, the Cruze isn't sporty, but it is pleasant and relaxing to drive. Consider the Cruze a mac-and-cheese compact: familiar and unpretentious, it is also comforting.
This Cruze is also well equipped, including leather seats and touch-screen navigation. It's also pricey, because Chevy decided to offer only one well-equipped version, which starts at $25,695.
G.M. estimates that the Cruze Diesel costs $3,000 more than a comparably equipped gasoline model. But the company insists that it still costs $695 less than a comparably equipped Jetta when that car is equipped with its optional automatic transmission.
A recent study by the University of Michigan Transportation Research Institute found that compared with gasoline cars, diesel versions saved from $2,000 to $6,000 in total costs over three to five years of ownership. Fuel savings and higher resale values are largely responsible. Research from the Edmunds.com car-buying site shows that a three-year-old Jetta TDI retains 5 percent more of its new-car price -- roughly $1,250 -- than a gas-powered model.
While that may prove true for the diesel Cruze as well, the Chevy won't bring spectacular savings at the pump. With diesel fuel still more expensive than regular unleaded, the E.P.A. figures an annual fuel cost of $1,750 for the Cruze diesel, just $250 less than the thrifty 1.8-liter gasoline version. Still, that leaves the diesel owner spending less than $34 a week in fuel to cover 15,000 miles in the Chevy, and stopping far less often, given the car's vast driving range.
Fans of popular German diesels have been making those calculations and deciding the higher initial investment is worth it. It will be interesting to see how many Chevy buyers are swayed by diesel's math, might and long-range stamina.
This article originally appeared in The New York Times.