WASHINGTON (AP) -- Is it time to return to the 55 mile-per-hour speed limit?

Republican Senator John Warner of Virginia is suggesting a national speed limit to save on gas, although he's not pushing a particular speed. Warner does cite studies that a 55 mile-per-hour limit would save two percent of highway fuel consumption a day. He's urging the Energy Department to determine the optimal speed.

The Energy Department's Web site says fuel efficiency drops sharply above 60 miles-per-hour. Warner says every five miles per hour above that costs drivers roughly the equivalent of paying 30 cents a gallon more at the pump.

A national speed limit has been tried before, starting in 1974, but was dropped in 1995 when crude oil fell to $17 a barrel and gasoline cost $1.10 a gallon.

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