General Motors' productivity improved 4.5% last year while Ford dropped to just a 3% improvement and DaimlerChrysler was up just 2.7%, ranking last among six major car makers rated, the annual Harbour Report said. The Harbour Report, first published in 1989 by the Troy, Michigan-based consultancy and released yesterday, measures assembly, stamping and powertrain productivity and rates North American vehicle makers on their assembly efficiency by dividing the number of vehicles produced in a factory by the number of hours worked by every worker from top executive to floor cleaner.