CNN: Following weeks of negotiation, President Bush signed into law Wednesday the first major increase in vehicle fuel efficiency standards in over three decades. The law also calls for greater use of biofuels like ethanol and more energy-efficient homes and appliances – but left out some provisions called for by Congressional Democrats. Automakers will have to make sure the average fuel efficiency level for all vehicles they sell in the U.S. is 35 miles per gallon by 2020, up from …