Tokyo, Japan—Nissan Diesel Motor Co. and the Tokyo Metropolitan Research Institute for Environmental Protection are jointly developing a filter for removing particulate matter from diesel-truck exhaust, reports Nikkei America. The filter is reportedly designed to remove nearly 90 percent of particulate emissions from diesel engines. Researchers now plan to fit the devices to prototype trucks to see how it affects fuel economy and test its long-term durability. Total cost of the truck and filter is about $135,000 (17 million yen); about $40,000 (5 million yen) is the cost of the filter. Company officials say the cost of the filter needs to be reduced to about $8,000 (1 million yen) to actually commercialize it.