It's the stuff kids dreams are made of and then some: shiny bikes, flashing lights, sirens -- and electric motors for greater speed. The UC Davis Police Department, which had its first bike officer in 1973, expanded its bike patrol unit last month from two officers to six and acquired six police bikes with electric motors. Purchase of the bikes was made possible by a $12,000 grant from the Yolo-Solano Air Quality Management District. The expanded bike patrol is expected to reduce the department's patrol car mileage by 16.7%, or 41,500 miles.