Few drivers slowing down to save gas

ST. PETERSBURG — You might wonder if skyrocketing gasoline prices are persuading drivers to slow down, maybe even adhere to the speed limit. But drive any major local highway and you'll see that isn't happening.

A St. Petersburg Times reporter driving the speed limit of 65 mph on Interstate 275 from downtown Tampa to St. Petersburg across the Howard Frankland Bridge last week might have been the only one driving under 70 mph.

Cars and trucks whizzed by —Lexuses, Nissans, Fords. Some tailgated before changing lanes and zooming away. A driver behind the wheel of a Chevrolet Trailblazer flashed the headlights in frustration before changing lanes and speeding off on the Howard Frankland.

The link between speeding and gasoline has drawn attention recently after U.S. Sen. John Warner, R-Va., asked the Department of Energy to study whether a lower national speed limit would conserve gasoline and reduce fuel prices.

In 1974, Congress set a national speed limit of 55 mph because of energy shortages caused by the Arab oil embargo. But that speed limit was repealed in 1995 when crude oil dipped to $17 a barrel and gasoline cost $1.10 a gallon. Now each state sets its own speed limit. In Florida, it tops out at 70 mph.

But gasoline now costs about $4 a gallon, and a barrel of oil costs around $145, prompting some, like Warner, to ask whether drivers could save fuel by slowing down.

The Energy Department says gas mileage usually drops over 60 mph, and that each 5 mph over 60 is equivalent to paying an extra 20 cents a gallon of gas. Consumer Reports found that a Camry dropped from 40 mpg to 35 when its speed rose from 55 to 65. At 75 mph, it lost another 5 mpg. One reason: aerodynamic drag increases the faster you drive, requiring more fuel to power the car through the air.

But other studies suggest that slowing down doesn't save much gas.

In 1987, tests by AAA showed little increase in gas consumption when rural speed limits were raised.

And a study released this year by the Congressional Budget Office found that high gas prices were not likely to make drivers slow down, and that drivers were not likely to save much money even if they did.

"The value of the potential fuel savings from slowing down is rather small compared with reasonable measures of many motorists' value of time, so the likely effect of gasoline prices on highway speeds also should be rather small," the study says.

The CBO cited one study by Oak Ridge National Laboratory that found drivers were likely to save just pennies on every commute by slowing down from 70 mph to 65 mph. And driving slower means you're driving longer.

So what does that mean for drivers going faster than 70 mph? That the only money they're likely to save will be from not getting tickets.

But try driving the speed limit on a local interstate. The Times reporter who did so came across just one car driving slower than 65 mph — a rickety truck in the middle lane of I-275 S near St. Petersburg.

It was tough to change lanes, though: too many cars were zooming by in the other lanes.

Information from the Associated Press and USA Today was used in this report. Abhi Raghunathan can be reached at araghunathan@sptimes.com or (727) 893-8472.

Few drivers slowing down to save gas 07/13/08 [Last modified: Tuesday, July 15, 2008 8:37pm]

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