U.S. road travel rose by 4 percent in the nation's warmest December on record, government data shows, and capped a record-setting driving renaissance amid cheap gasoline prices and lower unemployment. Defying expectations that rapid year-on-year increases in driving would abate as motorists got used to low pump prices, drivers logged 264.2 billion miles on U.S. roads and highways in December, the most ever for the month, according to the U.S. Department of Transportation.