Aug 04 2009

America's Other Obesity Epidemic

Posted by: Jonathan Marshall

Over the past decade, obesity-related health spending in America has doubled to about $150 billion a year, according to a new study. A similar epidemic has afflicted our vehicles for the past three decades, putting at risk efforts to achieve climate stability, cleaner air and energy security.

Daniel Sperling, director of the UC Davis Institute of Transportation Studies, noted in a recent speech that average car weight has increased 29 percent since the 1980s. Thanks to much heftier engines, the average car today manages to accelerate from 0 to 60 in a speedy 9.5 seconds, down from a leisurely 14.5 seconds in the 1980s. 

These trends help explain why auto and truck fuel economy, as measured by EPA, increased a mere 15 percent from 1980 to 2006.

According to Christopher Knittel at U. C. Davis, author of the new paper "Automobiles on Steroids," average mileage could have increased nearly 50 percent over that period if vehicle weight, horsepower and torque had stayed constant. In other words, the shift from light passenger vehicles to heavier and more powerful cars, SUVs and trucks almost completely masked some remarkable improvements in automotive efficiency.

This issue afflicts even cars that once exemplified thriftiness. For example, over the past 26 years, the venerable Honda Accord sold in the United States has increased in weight by more than 50 percent while tripling its horsepower.

This trend reflects in good measure the combination of low gasoline prices (cheaper than bottled water!) and Americans' love of power. The U.S. model 2009 Honda Accord gets at best a ho-hum 24 mpg, while British models, with smaller engines, get 31 mpg. The reason? Higher gasoline prices in the U.K. influence consumers to buy cars that economize on fuel.

With increasing weight, today's cars would be much more inefficient if automakers hadn't made great technological strides. Knittel estimates that a 3,000 pound car got about 10 mpg less in 1980 than in 2006. The problem isn't slow innovation but growing vehicle obesity.

Knittel concludes that the Obama administration's proposed new fuel economy standards are readily achievable if consumers would agree to put their cars on a diet. By merely shifting the mix of car and truck purchases back what they were in 1980 (fewer trucks, more cars), reducing vehicle weight and power gains since 1980 by just 25 percent, the average fuel economy of new vehicle fleets could meet 35.5 mpg with merely average rates of technological progress.

So the question is, will Americans rediscover the virtue of "small is beautiful?" The verdict is out--but the history of the late 1970s and last year's gasoline price spike suggests that Americans can see the beauty in more efficient cars when the price is right.

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