National 55 mph speed limit? How it impacts us

With national gas prices topping $4.00 a gallon, consumers are being forced to change their driving habits. Those habits could become law if congress agrees to implement a national 55 mph speed limit.

David Greene works with the Fuel Economy Information Program at Oak Ridge National Laboratory in Tennessee. The organization works closely with the Environmental Protection Agency regarding fuel economy.

Greene says such implementation would help us consume less fuel per mile because vehicles will experience less aerodynamic drag.

Aerodynamic drag is the force required to push the air out of the way of the vehicle as you drive. That force will increase with speed. So with most vehicles, reducing speed by five miles per hour would save about seven or eight percent of fuel, according to Greene.

Congress in 1974 set a national 55 mph speed limit because of energy shortages caused by the Arab oil embargo. The speed limit was repealed in 1995.

The National Academy of Sciences conducted a study of a 55 mph speed limit about ten years ago. According to Greene, that study concluded the speed limit saved about one to two percent of on gas use nationally.

Another positive of reducing speed, is the decrease of traffic fatalities. That's due to the fact that the probability of a fatal or serious injury increases the faster the vehicle is going when it crashes.

When it all comes down to it, it's a matter of consumers choosing more money or less time.

''I think that for most people, the value of their time would exceed the value of the fuel saved, even at $4.00 a gallon, but for some people it would be worth their wild,'' says Greene.

''It's hard to say nationwide how we'd come out on that; on average, our time is probably worth more than the fuel we're saving.''

Greene notes the main thing that will assist in energy consumption will come in the form of the Energy Independence and Security Act put in place by President Bush that will raise fuel economy standards by 40%. However, that will take time and will not be in place until 2020.

Greene, however, does have some tips on saving energy without having to slow down. That includes avoiding frequent acceleration and deceleration, limiting the amount of heavy items you carry in your car and maintaining proper tire inflation.