Ford's switch from nickel-metal hydride to lithium-ion batteries in its third-generation hybrid system will reduce its use of rare earth metals by up to 500,000 lb (225,000 kg) per year, the company says. Among the rare earths used in NiMH batteries are neodymium, cerium, lanthanum, and praseodymium—none of which are used in the new Li-ion batteries. Additionally, Ford has reduced its use of dysprosium by about 50% in magnets employed in the hybrid system's electric motors. Dysprosium is the most expensive rare earth used in Ford vehicles. This reduction is the result of a new diffusion process that is used in the magnet manufacturing process. The company says the Li-ion batteries are 30% less expensive, 25-30% smaller, and 50% lighter. The weight reduction results in better fuel efficiency for Ford's new 2013 C-MAX Hybrid (U.S. EPA certified at 47 mpg for both the city and highway cycles) and the Fusion Hybrid, which Ford projects will also achieve 47 mpg. A Ford spokesman told AEI that the company designed the batteries in house and assembles them at its Rawsonville Plant in Ypsilanti, MI—in keeping with the in-sourcing approach for the third-generation hybrid system.