Truck and engine maker Navistar Inc. has begun shipping 2010-compliant heavy-duty engines, including more than 225 tractors with its 13-liter MaxxForce engines, the company said.

Navistar International Corp. said Wednesday its fiscal third-quarter profit improved on higher military sales and better performance in its core truck segment.

Navistar Inc.’s top executive and its former finance chief will return more than $2 million in bonus pay to the company as part of a deal to settle federal charges of accounting misconduct.

Navistar Inc. attacked competitors’ 2010 engines on two fronts last week, telling environmental regulators that pollution controls on engines using selective catalytic reduction could be easily defeated and telling fleet managers that every gallon of diesel fuel an SCR engine saves will cost at least that much in diesel exhaust fluid consumed.

Truck and engine maker Navistar Inc. proclaimed the economical operating efficiency of its products during a Webcast Monday concerning what the original equipment manufacturer called “fluid efficiency.”

Navistar International Corp. more than doubled its net income during the three months ended April 30, even though the company’s second fiscal-quarter revenue dipped, compared with the same time last year.

Navistar International Corp. said Wednesday its fiscal second-quarter profit more than doubled, on higher truck and engine sales.

Navistar Inc. said Tuesday it will remain the exclusive provider of Class 8 tractors for truckload carrier Heartland Express.