Reuters: President Bush on Wednesday signed into law a landmark energy bill that increases US vehicle fuel efficiency for the first time in over three decades, significantly boosts ethanol use and phases out the traditional light bulb. The key part of the new law raises the gasoline mileage requirements of cars and trucks by 40 percent to an average 35 miles per gallon by 2020, which will eventually reduce US oil demand by 2 million barrels a day. The law also raises yearly production …