A report closely watched by carmakers shows Toyota and Daimler Chrysler's Chrysler Group among the best performers in automotive productivity.
The Harbour Report says Toyota improved its overall productivity by five and a-half percent in 2004. Chrysler has improved its productivity by 19 percent in the last three years.
Harbour Consulting in Troy says General Motors has made great strides and is the best performer of Detroit's Big Three.
GM says its results show a 22 percent productivity increase over the last five years.
The annual report measures productivity at North American auto plants. It has been released since 1989.