Plug-ins and Hybrids and Diesels, Oh My!

Two automotive conferences show the impact of public policy on core vehicle designs

5 min read

Public policy debates now affect every aspect of vehicle design, propulsion systems, and fuel usage. The scope and depth of these debates produced energetic discussions at two recent automotive conferences and led to some surprising questions.

For instance: How do U.S. drivers actually use their cars, and are government test cycles out of date? Does the United States require diesel engines to be too clean? Will the batteries developed for plug-in hybrids make regular old hybrids so affordable that plug-ins will never actually make sense? Could proposed European carbon regulations deal a mortal blow to the German auto industry? And how did London’s mayor inadvertently devastate the UK market for electric cars?

First, it turns out that Southern California drivers don’t drive the way the U.S. Environmental Protection Agency’s test procedures say they do. The EPA uses standard urban and highway driving cycles with patterns of acceleration, speed, braking, and idling that are now fairly well known to automotive regulatory engineers.

General Motors chose to use real-world driving data to model and benchmark its Chevrolet Volt extended-range electric vehicle, said Pete Savagian, director of engineering for GM hybrid power trains. He described a set of driving-cycle data, recently gathered from actual Southern California drivers in actual cars, to conferees at the Hybrid Vehicle Technologies Symposium, convened by the Society of Automotive Engineers (SAE) in San Diego in February.

What’s the bottom line? These drivers are tough on their cars—much tougher than the test drivers using the EPA’s regulatory cycles. And they drive very differently from the greenest of Toyota Prius drivers, who often attempt to keep their cars in electric mode as long as possible.

Why are these data significant? Like other sprawling suburban areas connected by freeways and six-lane arterials, Southern California lends itself to a rapid mix of high-speed driving and bursts of stop-and-go traffic—and its drivers are impatient. This pattern is much more reflective of how average U.S. drivers behave.

What, asked Savagian, was the median freeway speed based on actual Southern California driving data? The answer was 83 miles per hour (133 kilometers per hour). As Savagian remarked solemnly, ”Drivers in L.A. turned out to be very, ah, aggressive .”

As for diesel technologies, a panel at the Auto FutureTech Trade Fair—a new branded sub-track of the long-standing Globe Foundation conference on business and the environment, held in Vancouver in March—acknowledged that perhaps the biggest single issue for automakers is whether U.S. buyers will take to a new wave of ”clean diesel” vehicles over the next three years. Those engines will have far more complex and expensive emissions systems to meet U.S. limits on emissions of nitrous oxides (NOx) and particulate matter—the world’s most stringent guidelines.

More than half the cars sold in Europe are now diesels, but none of them are legal in the United States under the EPA’s Tier 2, Bin 5 restrictions. European makers see diesel’s greater efficiency as the obvious way to reduce both U.S. fuel consumption and global carbon emissions. And Europeans quietly pooh-pooh hybrid electric vehicles as expensive and needlessly complex.

But, asked one participant, can diesels ever hope to meet the ”super-ultralow” or ”partial zero” emissions levels already achieved by the Prius and even some nonhybrid gasoline cars? Timothy V. Johnson of Corning—a major producer of ceramics for diesel emissions controls—reminded the questioner that public health is now far more affected by particulate matter than the pollutants known as criteria emissions (nitrous oxides, carbon monoxide, and hydrocarbons). And, he said, a Prius now emits more particulates than the new clean diesels.

Taking the point further, Johannes-Joerg Rueger, of European component maker Robert Bosch, noted that emissions from today’s vehicles are 90-plus percent lower than in the past. ”We are literally at zero compared to 30 years ago,” he said. ”No one cared about carbon dioxide then. Now is it necessary to go still further on these low levels of criteria emissions?”

The subtext: European makers think the United States is overly fixated on reducing emissions at the expense of cutting carbon. Nonetheless, the obvious truth is that in the United States, no politician is likely to go on record proposing to increase allowable vehicular emissions.

Back on the hybrid front, Honda’s John German suggested that the hype around plug-in hybrid electric vehicles (PHEVs) threatens to obscure the most efficient way to reduce or displace petroleum usage: replacing regular vehicles with hybrids. He framed the argument by noting that the United States measures fuel usage the wrong way—in distance per unit of fuel, rather than measuring the amount of fuel needed to go a set distance, which makes it easier to calculate the effects of consumption-reducing changes.

To illustrate, he pointed out that raising the mileage of a large SUV from 10 miles per gallon to 20 mpg saves five gallons of gasoline for every 100 miles traveled. Doubling the gas mileage of a hybrid, from 50 mpg to 100 mpg, saves just a single gallon per 100 miles. (In the metric system, the fuel savings improve from about 24 liters per 100 kilometers to about 12 L/100 km.) German added that the battery advances making plug-in hybrids practical will have an even greater impact on batteries for regular hybrids, vastly reducing their cost. Hence his conclusion: persuading drivers of low-mileage vehicles to buy hybrids will displace far more petroleum—at a far lower battery cost—than adding plug-in capability to the same number of high-mileage hybrids. (Carmakers will most likely try to do both at the same time, of course.)

For much of the year, the European Union has wrestled with proposals to limit automakers’ fleet emissions of carbon dioxide (CO 2 ). This possibility has been much on the minds of German auto engineers in particular; the carmakers of France and Italy specialize in smaller cars, so they would not have great difficulty meeting the proposed fleet limit of 120 grams of CO 2 per kilometer.

But Germany’s automakers—Audi, BMW, Mercedes-Benz, and Volkswagen—have far higher fleet averages and strongly resist a single limit per manufacturer. Instead, they have fought for a scale of CO 2 limits based on a car’s ”footprint,” or the area of road it occupies. While fears of the destruction of the German car industry seem far-fetched, the impact of restrictions on its products could be very real, just as the anticipation of new U.S. requirements for fuel economy by 2020 have caused U.S. automakers to recast their future product plans.

Meanwhile, several discussions at Auto FutureTech focused on London mayor Ken Livingstone (subsequently defeated in a May election). He had previously instituted the world’s first ”congestion charge,” requiring vehicles to pay US $15 or more to enter the central city during business hours. The scheme is widely credited with reducing traffic and speeding surface public transport.

Recently, Livingstone proposed to add fees of US $100 or more on high-emitting vehicles—including large luxury SUVs, derisively known as ”Chelsea tractors”—and exempt vehicles having CO 2 emissions under 120 grams per kilometer from the charge altogether. Previously, only zero-emission (that is, electric) and a few alternative-fuel vehicles were exempted, which led to a proliferation of two-seat electric runabouts in central London. Now Livingstone, in the words of one conferee, has accidentally managed to ”throw electric cars under the bus” by extending their zero-CO 2 exemption to low-CO2 cars with combustion engines. Many European carmakers now have one or more models having emissions below that level, generally small turbo diesels. One, for example, is theVolkswagen Polo BlueMotion, at a mere 99 g/km.

And so it goes: policy and auto engineering, unwilling bedfellows, married forever.

About the Author

John Voelcker has written about automotive technology and other topics for 20 years. He covered software and microprocessor design for IEEE Spectrum from 1985 to 1990.

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