The U.S. demand for hybrids and plug-ins is again ruled by domestic automakers, plug-in vehicle sales surged about 45% to almost 15,000 units. In addition to Tesla, which continues to boost sales but doesn't publish monthly metrics, Ford and General Motors each performed well in May. Green-car sales for the Blue Oval rose 56 percent from a year earlier to 9,221 vehicles, as Fusion Hybrid sales more than doubled, while Ford C-Max Energi plug-in hybrid sales jumped 77 percent. Up the road, General Motors increased green-car sales by 50 percent to 3,964 vehicles. Notably, the Chevrolet Bolt electric-vehicle model had a record month, tallying 1,566 unit sold in May. While the Chevrolet Volt extended-range plug-in sales fell slightly to 1,817 units, Chevy Malibu Hybrid sales doubled to 493 units.