Automaker General Motors Co. said that it was planning to invest $494 million to revamp the fuel efficiency of its engines.

For re-engineering of its four-cylinder Ecotec engine, the company would also recall 565 employees in three of its plants in the US including an investment of $425 million and recall of 470 workers at its engine plant in Tonawanda, New York.

Plants at Defiance, Ohio, and Bay City, Michigan, are the other plants featuring in the plan. GM intends to invest $59 million in Defiance plant and $10.5 million in the Bay City plant.

The money would be spent on renovations, special tooling, equipments and machinery.

With the Ecotec engines the Detroit-based automaker is planning to replace its larger engines to fulfill the fuel-economy regulations, which expect vehicles to have an increased average of 35.5 miles a gallon by year 2016.

Vice President of labor relations in GM, Denise Johnson said in a statement that GM at present is changing its product basket to include vehicles high on fuel efficiency and low on emissions. The Ecotec engine is a key component in the company's transformation plans.