Light-Duty Diesels Ready for Prime Time

It’s taken a few decades, but the planets finally have aligned properly for light-duty diesels to see mainstream success in the U.S.

It has not been easy. While 50% or more light vehicles in Europe are powered by diesels, the U.S. has given them a consistently hostile reception even though they are 20% to 30% more efficient than comparable gasoline engines.

Some critics blame General Motors’ poorly engineered V-8 diesel from the 1980s for ruining the compression-ignition engine’s reputation, but for most U.S. consumers that debacle is unknown ancient history.

U.S. and California tailpipe emissions regulations limiting smog-causing oxides of nitrogen – much tougher than Europe’s – have created the biggest hurdles for acceptance of diesels in the U.S.

To many auto makers that sell diesels elsewhere, marketing them in the U.S. simply is too complicated and expensive to be worth the effort.

While much of the world celebrates diesels for their durability and ability to reduce carbon-dioxide emissions better than gasoline engines, diesel-powered cars actually have been shut out of the California market for years at a time.

Even auto makers such as Volkswagen – which sells more than 2 million diesel-powered cars around the globe – quit offering diesel cars in California for a while because it could not keep up with the state’s ever-increasing limitations on NOx and hydrocarbon emissions.

Only a few years ago, proponents worried California’s upcoming Level III low-emissions-vehicle rules – the strictest in the world – would doom passenger-vehicle diesels in the U.S.   

But thanks to selective catalytic reduction, advanced particulate control devices and a federal mandate for ultra-low sulfur diesel fuel in the U.S. that allows these emissions control systems to work properly, diesels can meet LEV III, Euro 6 and whatever other emissions standards are coming down the road.

This is very good news indeed for auto makers faced with meeting corporate average fuel economy standards and for consumers who deserve to have high-efficiency powertrain choices other than boring hybrid-electric vehicles.

European auto makers already are paving the way, with U.S. diesel installation rates as high as 80% on some Volkswagen models and 30% on luxury cross/utility vehicles, where the engines deliver the fuel economy of a compact car and twice the range of a typical CUV.

On a recent test drive of a VW Touareg CUV, I averaged 27.4 mpg (8.6 L/100 km). A midsize CUV with a gasoline engine making a comparable 406 lb.-ft. (550 Nm) of torque could not come close to such efficiency.

The benefits of diesel engines are so obvious, Audi of America is making the alternative powertrain a key part of a new U.S. marketing strategy.

“We are waiting for far more universal adoption of diesel in the United States for its fuel efficiency,” Scott Keogh, president and CEO of Audi of America says at the recent CAR Management Briefing Seminars in Traverse City, MI.

Even more significant is the fact mainstream brands such as Chevrolet, Jeep and Mazda are offering diesels in affordable vehicles, signaling the U.S. marketplace truly is ready to accept a technology most of the world already has embraced.

I’m convinced diesels are ready for prime time in the U.S. after test driving a new Chevrolet Cruze Turbo Diesel.

GM claims the sedan gets 46 mpg (5.1 L/100 km), the best highway mileage of any non-hybrid in the U.S.

I drove the car 253 miles (407 km), and it exceeded the highway mileage number on its sticker. The trip computer registered 46.7 mpg (5.0 L/100 km) with an average speed of 64.9 mph (104 km/h). In case you haven’t heard, hybrids do not usually come close to hitting their official fuel-efficiency numbers.

I was even more impressed by how little fuel the Cruze burned: only a quarter-tank. After 150 miles (241 km), the fuel indicator needle had not budged, and I honestly thought the gauge was broken.

At $25,795 (including $810 destination charge), the car is well-equipped, including leather upholstery and wonderfully firm and supportive seats that are perfect for long-distance haulers. What’s more, the 2.0L engine produces up to 280 lb.-ft. (380 Nm) of torque and is lots of fun to drive, something you can’t say about most hybrids.

The only thing wrong with the compression-ignition engine is it was invented in 1893. If it had been developed by Elon Musk last year, Congress would be drafting legislation requiring every auto maker to offer diesel engines.

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