Automakers today find themselves in something of an unenviable position.
Strict corporate average fuel economy rules continue to ratchet up, while President Trump may—or may not—attempt to change those rules.
Until the uncertainty resolves, however, automakers have to stick with their plans to meet CAFE standards through 2025.
And even if U.S. regulations change, the rest of the world almost surely won't alter theirs—making fuel efficiency just as important as ever.
Last week, GM's vice president for global propulsion systems, Dan Nicholson, discussed the company's launch of a new 1.6-liter 4-cylinder diesel engine from Europe.
“Diesels are, and will play, an important part in our overall CAFE targets and goals," he told media.
2016 Chevrolet Cruze unveiling, Detroit, June 2015
But making diesels a significant part of the Cruze lineup will require changing the minds of buyers about diesel technology at a time when European governments are actively turning against the technology for its past emission sins.
GM, however, says it has built refinements into its Hungarian-built engine that promise not just impressive performance and fuel economy but a healthy reduction in carbon-dioxide emissions.
While the obvious calling card for the new engine is fuel-economy ratings in which GM touts the 52-mpg highway number, it's just as proud of its work reducing engine noise and vibration.
GM says the new engine is dramatically quieter than the company's last small four-cylinder diesel, a 2.0-liter 4-cylinder unit sold the first-generation and low-volume Cruze Diesel.
That could explain the German automotive media's nickname for this engine's European version: "flüsterdiesel," literally “whisper diesel” in German.
At idle, GM claims the engine produces just half the noise of the 2.0-liter, and the reduction only increases with engine speed: noise drops 55 percent at 2,500 rpm, rising to 68 percent at 4,000 rpm.
2017 Chevrolet Cruze Hatch
Since the new 1.6-liter engine loses nearly a quarter of its predecessor's displacement, we might have expected a drop in power along with the improved fuel economy.
Indeed, the new engine is rated at 137 horsepower (the old one was 151 hp, in a heavier car) and produces 240 lb-ft of torque, against the old engine's 264 lb-ft in normal driving (or a temporary 280 lb-ft in "overboost" mode).
While it's down a bit on power, GM is quick to point out that the new engine produces more torque per liter: 150 lb-ft per liter in the 1.6, versus 132 in the old 2.0-liter.
And, of course, it's much more efficient: the EPA rates it at 30 mpg city, 52 mpg highway, and 37 mpg combined when fitted with the standard 6-speed manual gearbox. That's an increase of 3 mpg city, 6 mpg highway, and 5 mpg overall.
Adding the optional nine-speed automatic drops the highway rating to 47 mpg but increases the city figure to 31 mpg.
Take those numbers with a pinch of salt, of course. "Many customers will exceed that [highway] fuel economy rating," said assistant chief engineer Mike Siegrist, citing personal experience.
2018 Chevrolet Equinox
Is the increased torque, 52-mpg highway rating, and quiet performance worth the $2,800 premium Chevrolet is demanding for the Cruze Diesel? It's hard to say.
If your commute involves nothing but freeway driving, that 52-mpg highway is tantalizing.
But if you live in a city like Los Angeles where the average freeway speed is 12 miles per hour, it's difficult to recommend a diesel that returns the same city fuel economy as the less expensive gasoline engine.
But for Chevrolet, the diesel doesn't need to be a runaway success. Chevy's spokespeople said it will be happy if the Cruze Diesel matches the 9-percent take rate it sees for the Colorado and GMC Canyon diesels.
All Cruze Diesels are fitted with selective catalytic reduction exhaust aftertreatment, using liquid urea, and run on diesel fuel with up to 20 percent biodiesel, known as B20.