WASHINGTON -- Back in the good old days when the price of gas in Seattle was a mere $1.50 a gallon, miles-per-gallon weren't so important. The number was a curiosity, the basis for bragging rights and mental exercise during long trips. That was two years ago. Today, with the price of gas pushing beyond $2.45 a gallon in the Puget Sound region and federal projections saying it will reach $3 this summer, the miles-per-gallon estimates calculated by the Environmental Protection Agency have taken on a new prominence in a nation suddenly intent on squeezing every mile out of its cars....