WASHINGTON (Reuters) – Trucks and buses in the United States may have to be equipped with devices to limit their speed under a proposed rule issued on Friday by the U.S. Transportation Department which said the move could save both lives and fuel. The department will weigh setting speed limits at 60, 65 or 68 miles per hour for heavy commercial vehicles, but said it will consider other speeds based on comments from the public. Speed limits on interstate highways vary across the United States, with some states allowing vehicles to drive as fast as 85 mph (137 km per hour), though many states have lower maximum speeds for trucks. “There are significant safety benefits to this proposed rulemaking,” Transportation Secretary Anthony Foxx said in a statement. “In addition to saving lives, the projected fuel and emissions savings make this proposal a win for safety, energy conservation, and our environment.” The American Trucking Association, a trade group for the industry, praised the proposal, and noted that it had petitioned the National Highway Traffic Safety Administration in 2006 to require speed limiting technology. The group has endorsed a national speed limit of 65 mph (105 kph) for trucks.