How to kick the oil habit
17 May 2006
NewScientist.com news service
Francis Slakey

THE world is running out of oil. That much is scarcely in doubt, even if it is less clear just how long it will take. Nowhere is this predicament felt more keenly than in the US, where consumers are having to pay a record $3 for a gallon of gasoline. This might seem a pittance to Europeans used to paying twice that, but in the great car economy that is America it amounts to something of a crisis.
Members of Congress embarrassed themselves recently trying to soothe the nation's energy anxiety. Their proposals ranged from an investigation into oil companies allegedly fixing prices, to slipping $100 under every taxpayer's pillow. The mantra of the moment appears to be: "There is no quick fix to rising gasoline prices."

Well, there is a quick fix. In one decisive act, the government could save in excess of 50 million gallons of gasoline a day - that's more than a billion barrels a year, which is more than the US imports annually from the Persian Gulf. The magic solution? Lower the national speed limit to 55 miles per hour.

“In one decisive act, the US could save more than 50 million gallons of gasoline a day”
Here's why it would work. Every car engine has a sweet spot in terms of efficiency, typically when running at 55 mph. Beyond 60 mph, engine efficiency plummets because of higher temperatures. In addition, three other factors that affect gasoline consumption become more significant at higher speeds: tire resistance, wheel bearing friction and air drag. What all that means is that for the average car, cutting the speed from 75 mph to 55 mph improves fuel efficiency by roughly 25 per cent.

The laws of physics do not always make for pleasant policy. Ask former president Jimmy Carter, who endorsed a 55 mph limit when upheaval in the Middle East led to an oil crisis in the 1970s. The public groaned, then kicked him out of office, along with the policy. Lowering the speed limit did reduce demand and it did help cut gasoline prices. For policy-makers the key question has always been: at what point does the benefit outweigh the pain?

The arguments against a 55 mph limit have not changed. First, there is the libertarians' slippery-slope concern. If the government limits the speed citizens can drive in order to save fuel, what's next? Will it cap the number of miles we can drive? Will it outlaw Hummers and similar gas-guzzlers? There is, however, a big difference between capping speeds and limiting miles or banning Hummers. There are already speed limits, imposed by each state, which are there to advance a generally recognised public good: safety. Reducing the limit to 55 mph across the nation simply broadens the sense of public good to include conservation.

What about commuters who complain that their journey to work will be longer and more dreadful? How that should weigh in the balance depends on how precious you think a few minutes are. The average work commute is less than half an hour, with only a fraction of that time spent on the highways where the new speed limits would apply. For most of us, a reduced limit would add only about as much time as it takes to butter the morning toast.

The impact would be greatest on long-haul commuters, truckers and holiday-makers: for example, on a family driving cross-country to Yellowstone park. For them it would be a matter of trade-offs. Yes, they would spend more time on the road, but they would spend less money on gasoline: at current prices, they would save more than 50 cents per gallon. Despite the obvious inconvenience, lowering the speed limit would start to make sense for most people because the net oil savings are huge - reducing demand by a billion barrels a year would cut prices.

There is just one flaw in this plan: the ordinary consumer is the only one who pays. In the interests of fairness, industry would have to play its part, too. President Carter achieved this in 1975 by passing a law forcing US car makers to establish an average fuel efficiency standard across their fleet of 27.5 miles per gallon (11.7 kilometres per litre) within a decade. Known as the Corporate Average Fuel Efficiency (CAFE) standard, it has been fixed ever since. It shouldn't have been: if the standard had tightened over the years in step with progress in engine design, inching up to, say, 33 miles per gallon today, the nation would be saving 2 million barrels of oil a day. There could be an incentive too for manufacturers to improve an engine's sweet spot to make it run more efficiently at 75 mph.

President Bush's diagnosis is that "the nation is addicted to oil". He should remember that it takes bold action to kick an addiction.

From issue 2551 of New Scientist magazine, 17 May 2006, page 21