Volkswagen’s emissions cheating scandal rocked the automotive world when it broke last year. It was the industry’s biggest story of 2015, and it’s one that’s still unfolding today.
The long-term effects of this duplicitous deed have yet to be determined, but there could be significant fallout, and not just for the “people’s car” company. Rival automakers that also sell vehicles with compression-ignition powerplants could feel the squeeze as well should consumers start sidestepping diesel engines.
When asked if the humble diesel’s reputation has been irreparably tarnished, Wolfgang Stütz, general manager of advanced development for diesel engines at BMW said, “It’s too early to say this, but maybe.”
To date, the Bavarian automaker has not suffered any consequences. “At the moment, there is no negative influence to see for BMW diesel engines,” said Stütz. “We sell it very well, especially in Europe, and there is no influence at the moment.”
“If you look at Europe,” explained Stütz, “it’s the main market for diesel engines. We have more than 80 percent diesel cars in Europe.” However, things are totally different on this side of the Atlantic.
“In the United States, on the other hand, there are about 5 percent diesel engines,” he said, which works out to around 20,000 units annually. For reference, on a global basis, BMW’s product mix is about 40 percent diesel-powered.
From a growth standpoint, these figures are curiously flat in both America and Europe. In the case of the U.S., it’s because of low fuel prices; consumers aren’t really concerned with the superior mileage or torque offered by these engines and, consequently, are unwilling to pay a premium for diesels. In Europe, Stütz noted that it’s due to an already very high market share, which makes significant growth difficult.
BMW has a dizzying array of compression-ignition engines in the Old World. Fortunately, in ‘Murica, things are a little simpler. The company offers a 2.0-liter four-cylinder diesel in the 3 Series range as well as the X3 crossover. It’s good for an impressive 180 horses. Larger models including the 5 Series and the X5 can be had with a 3.0-liter inline six. This diesel puts out a muscular 255 horsepower.
More Work to Do
Still, compression ignition is not something on a lot of drivers’ minds, especially in North America, where gasoline is the dominant motoring fuel. “We have to improve the image of diesel engines,” explained Stütz, something the VW situation isn’t helping with. “We see a big future for diesel engines and the reason is that diesel engines are a CO2 [reduction] concept.”
“Modern diesel engines emit more than 20 percent less CO2 than modern petrol engines, and so, this can be a very big influence for the environment, the future also,” said Stütz.
This is the case because these powerplants are more efficient than their gasoline rivals. Burning a more energy-dense fuel, running much higher compression ratios and having lower pumping losses are a handful of reasons why.
The Letter of the Law
Circling back to the emissions-related problems facing its rival, Stütz noted, “An important statement is that we fulfill … every legal standards (sic) in the world with our engines,” which, of course, includes the U.S.
In decades past, diesel engines were notoriously dirty, emitting plumes of choking black smoke. But this is no longer the case. Things like particulate filters and selective catalyst reduction (SCR) have made these powerplants remarkably clean. Thanks to modern after-treatment systems, Stütz said particulate emissions can actually be lower with diesels than gasoline engines.
Compression-ignition engines are clean, but they’ll have to do even better going forward. “This general trend we see, that all over the world, the legislation will be stronger and stronger [for emissions],” said Stütz.
“At the moment, legislation in the United States is the strongest legislation and we fulfill this legislation with technology, which is sustainable for the future also.” Continuing, Stütz explained that BMW’s current emissions-control systems will continue to be refined and improved in order to keep its diesel engines compliant.
Beyond particulate filters and SCR there are no radical new diesel emissions technologies on the horizon. Further clarifying his point Stütz said, “There is a lot of development work to improve these systems, but in principle we have [these] systems for the future.”
“We have two-stage turbocharging [for] more than 10 years and we will continue in this improvement of turbocharging,” explained Stütz. He also said more advanced high-pressure fuel-delivery systems will further refine the breed, calling this “an important puzzle [piece] for the future.” Of course, electrification is always an option as well.
But not necessarily hybrids. Pairing an electric motor, battery pack and power-control system with a diesel is exorbitantly expensive, given that the engine itself is already appreciably pricier than a gasoline powerplant. But Stütz said 48-volt electrical systems, which are in development by numerous companies, could be “an important milestone for the future.”
Think of these amped-up systems as a stepping stone. They can enable a wide array of new technologies, from mild-hybrid functionality to regenerative braking to more effective stop-start, all of which improve vehicle efficiency without breaking the bank. Forty-eight-volt technology can also enable automakers to implement things like electrically driven air conditioning compressors and water pumps, further slashing fuel consumption.
Whether it’s electrified or not, diesel cars seem safe for the time being, at least at BMW.
“In principle, there could be a great future for the diesel engines,” said Stütz, adding that they’re ideal for large vehicles and long-distance driving. According to him, diesels have a lot of life left in them.
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